Awesome, you'll have to avoid stuff like torpedo tubes and probably even turreted secondaries, perhaps just put 4.7 AA guns on the side as an early DP mount? I know that having 3 turrets is heavier, but the RN probably wouldn't want to risk a ship having 50% of its armament knocked out if it looses a turret.

first try:

hms unaprochable, Britain battlecruiser laid down 1923

Displacement:

18.611 t light; 19.455 t standard; 20.582 t normal; 21.484 t full load

Dimensions: Length overall / water x beam x draught

736,04 ft / 735,00 ft x 81,00 ft x 22,00 ft (normal load)

224,35 m / 224,03 m x 24,69 m x 6,71 m

Armament:

6 - 13,50" / 343 mm guns (2x3 guns), 1.230,19lbs / 558,00kg shells, 1923 Model

Breech loading guns in turrets (on barbettes)

on centreline ends, evenly spread

10 - 4,00" / 102 mm guns in single mounts, 32,00lbs / 14,51kg shells, 1923 Model

Breech loading guns in deck mounts

on side, all amidships

Weight of broadside 7.701 lbs / 3.493 kg

Shells per gun, main battery: 100

2 - 18,0" / 457,2 mm above water torpedoes

Armour:

- Belts: Width (max) Length (avg) Height (avg)

Main: 9,00" / 229 mm 477,75 ft / 145,62 m 10,80 ft / 3,29 m

Ends: 3,00" / 76 mm 257,23 ft / 78,40 m 10,80 ft / 3,29 m

Upper: 8,00" / 203 mm 477,75 ft / 145,62 m 8,00 ft / 2,44 m

Main Belt covers 100 % of normal length

Main belt does not fully cover magazines and engineering spaces

- Torpedo Bulkhead:

1,00" / 25 mm 477,75 ft / 145,62 m 20,19 ft / 6,15 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)

Main: 8,00" / 203 mm 4,00" / 102 mm 8,00" / 203 mm

2nd: 1,00" / 25 mm 1,00" / 25 mm -

- Armour deck: 2,00" / 51 mm, Conning tower: 9,00" / 229 mm

Machinery:

Oil fired boilers, steam turbines,

Geared drive, 2 shafts, 111.275 shp / 83.011 Kw = 31,00 kts

Range 8.000nm at 12,00 kts

Bunker at max displacement = 2.028 tons

Complement:

858 - 1.116

Cost:

£5,762 million / $23,048 million

Distribution of weights at normal displacement:

Armament: 963 tons, 4,7 %

Armour: 6.454 tons, 31,4 %

- Belts: 3.549 tons, 17,2 %

- Torpedo bulkhead: 357 tons, 1,7 %

- Armament: 865 tons, 4,2 %

- Armour Deck: 1.537 tons, 7,5 %

- Conning Tower: 146 tons, 0,7 %

Machinery: 3.719 tons, 18,1 %

Hull, fittings & equipment: 7.475 tons, 36,3 %

Fuel, ammunition & stores: 1.971 tons, 9,6 %

Miscellaneous weights: 0 tons, 0,0 %

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship):

20.670 lbs / 9.376 Kg = 16,8 x 13,5 " / 343 mm shells or 3,0 torpedoes

Stability (Unstable if below 1.00): 1,25

Metacentric height 5,5 ft / 1,7 m

Roll period: 14,5 seconds

Steadiness - As gun platform (Average = 50 %): 52 %

- Recoil effect (Restricted arc if above 1.00): 0,50

Seaboat quality (Average = 1.00): 1,04

Hull form characteristics:

Hull has a flush deck

Block coefficient: 0,550

Length to Beam Ratio: 9,07 : 1

'Natural speed' for length: 27,11 kts

Power going to wave formation at top speed: 51 %

Trim (Max stability = 0, Max steadiness = 100): 50

Bow angle (Positive = bow angles forward): 2,00 degrees

Stern overhang: 0,00 ft / 0,00 m

Freeboard (% = measuring location as a percentage of overall length):

- Stem: 29,82 ft / 9,09 m

- Forecastle (20 %): 18,98 ft / 5,79 m

- Mid (50 %): 18,98 ft / 5,79 m

- Quarterdeck (15 %): 18,98 ft / 5,79 m

- Stern: 18,98 ft / 5,79 m

- Average freeboard: 19,85 ft / 6,05 m

Ship tends to be wet forward

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 124,7 %

- Above water (accommodation/working, high = better): 172,1 %

Waterplane Area: 41.549 Square feet or 3.860 Square metres

Displacement factor (Displacement / loading): 95 %

Structure weight / hull surface area: 128 lbs/sq ft or 624 Kg/sq metre

Hull strength (Relative):

- Cross-sectional: 0,83

- Longitudinal: 0,80

- Overall: 0,81

Caution: Hull subject to strain in open-sea

Hull space for machinery, storage, compartmentation is cramped

Room for accommodation and workspaces is excellent

second try with higher tonnage:

hms unaprochable, Britain battlecruiser laid down 1923

Displacement:

24.802 t light; 25.777 t standard; 27.120 t normal; 28.194 t full load

Dimensions: Length overall / water x beam x draught

791,08 ft / 790,00 ft x 90,00 ft x 25,00 ft (normal load)

241,12 m / 240,79 m x 27,43 m x 7,62 m

Armament:

6 - 13,50" / 343 mm guns (3x2 guns), 1.230,19lbs / 558,00kg shells, 1923 Model

Breech loading guns in turrets (on barbettes)

on centreline ends, majority forward, 1 raised mount - superfiring

10 - 4,00" / 102 mm guns in single mounts, 32,00lbs / 14,51kg shells, 1923 Model

Breech loading guns in deck mounts

on side, all amidships

Weight of broadside 7.701 lbs / 3.493 kg

Shells per gun, main battery: 100

2 - 18,0" / 457,2 mm above water torpedoes

Armour:

- Belts: Width (max) Length (avg) Height (avg)

Main: 9,00" / 229 mm 513,50 ft / 156,51 m 11,38 ft / 3,47 m

Ends: 3,00" / 76 mm 276,48 ft / 84,27 m 11,38 ft / 3,47 m

Upper: 8,00" / 203 mm 513,50 ft / 156,51 m 8,00 ft / 2,44 m

Main Belt covers 100 % of normal length

Main belt does not fully cover magazines and engineering spaces

- Torpedo Bulkhead:

1,00" / 25 mm 513,50 ft / 156,51 m 22,69 ft / 6,92 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)

Main: 8,00" / 203 mm 4,00" / 102 mm 8,00" / 203 mm

2nd: 1,00" / 25 mm 1,00" / 25 mm -

- Armour deck: 2,00" / 51 mm, Conning tower: 9,00" / 229 mm

Machinery:

Oil fired boilers, steam turbines,

Geared drive, 2 shafts, 127.974 shp / 95.469 Kw = 31,00 kts

Range 8.000nm at 12,00 kts

Bunker at max displacement = 2.417 tons

Complement:

1.056 - 1.373

Cost:

£6,620 million / $26,479 million

Distribution of weights at normal displacement:

Armament: 963 tons, 3,5 %

Armour: 7.491 tons, 27,6 %

- Belts: 3.954 tons, 14,6 %

- Torpedo bulkhead: 431 tons, 1,6 %

- Armament: 1.123 tons, 4,1 %

- Armour Deck: 1.809 tons, 6,7 %

- Conning Tower: 175 tons, 0,6 %

Machinery: 4.277 tons, 15,8 %

Hull, fittings & equipment: 12.071 tons, 44,5 %

Fuel, ammunition & stores: 2.317 tons, 8,5 %

Miscellaneous weights: 0 tons, 0,0 %

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship):

38.553 lbs / 17.487 Kg = 31,3 x 13,5 " / 343 mm shells or 5,2 torpedoes

Stability (Unstable if below 1.00): 1,22

Metacentric height 6,2 ft / 1,9 m

Roll period: 15,2 seconds

Steadiness - As gun platform (Average = 50 %): 54 %

- Recoil effect (Restricted arc if above 1.00): 0,40

Seaboat quality (Average = 1.00): 1,09

Hull form characteristics:

Hull has a flush deck

Block coefficient: 0,534

Length to Beam Ratio: 8,78 : 1

'Natural speed' for length: 28,11 kts

Power going to wave formation at top speed: 50 %

Trim (Max stability = 0, Max steadiness = 100): 50

Bow angle (Positive = bow angles forward): 2,00 degrees

Stern overhang: 0,00 ft / 0,00 m

Freeboard (% = measuring location as a percentage of overall length):

- Stem: 30,92 ft / 9,42 m

- Forecastle (20 %): 19,67 ft / 6,00 m

- Mid (50 %): 19,67 ft / 6,00 m

- Quarterdeck (15 %): 19,67 ft / 6,00 m

- Stern: 19,67 ft / 6,00 m

- Average freeboard: 20,57 ft / 6,27 m

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 100,7 %

- Above water (accommodation/working, high = better): 171,0 %

Waterplane Area: 48.883 Square feet or 4.541 Square metres

Displacement factor (Displacement / loading): 114 %

Structure weight / hull surface area: 177 lbs/sq ft or 863 Kg/sq metre

Hull strength (Relative):

- Cross-sectional: 1,14

- Longitudinal: 1,03

- Overall: 1,06

Hull space for machinery, storage, compartmentation is adequate

Room for accommodation and workspaces is excellent