Plausibility Check: Post USSR Russia with worlds 3rd biggest economy

To put them over Japan would require GDP per capita around the 35,000 range. With better luck and leadership is this possible or considered ASB territory?
Uh if they kept the annexed land it would certainly help, especially since it increases sea access. Then it's a matter of leadership.
Very doubtful. Soviet economy was pretty much ruined. You can avoid that all shit caused by sudden transition to capitalism but still you are far from 3rd largest economy.
No chance. There aren't enough Russians. Maybe if most of the USSR (Russia, Ukraine, Belarus, Central Asia, maybe parts of the Caucuses) remained territorially together (...CIS) the resulting Union would be able to surpass Japan eventually. But Russia is too small and in too bad of a condition in 1991 to surpass Japan.