Ok... I will let my own political bias speak for me here, but you know the meme here on AH.com of 'Notzis'? In which people more or less some up with TLs such as
'What if the Nazis were less racists against Slavs, and actually came to the people of Ukraine and the Baltics as liberators from the Soviets?' or
'What if the Confederacy won the American Civil War, abolish slavery right afterwards, and become a prosperous developed industrialized nation with friendly relations with the US?'.
With the simple answer being
'Then this alternate polity that you propose will not be the Nazis/CSA anymore, since it fundamentally changes their founding principles.'
I would argue on an ideological level, 'extremely wholesome' and 'Soviet style Marxist–Leninism' are mutually exclusive. At best, you might get a 'ruthless and brutal, but fair' Stalin, one that still engages in paranoid purges against his rivals (Since I would argue that paranoia was a core part of who Stalin was as a person.... And granted, if he wasn't so paranoia, he might never made it to a position of power in the first place), but kill less innocent people, and especially avoid imprisoning members of the intelligentsia such as Sergei Korolev, so that their work would not have been needlessly interrupted by imprisonment. Besides that, no Lysenkoism, the rejection of genetics on ideological grounds, and the politicization of science will also be a must, in order for Stalin to approach anything even remotely 'wholesome'.
Besides that, no crimes against humanity such as the deportation/forced displacement and Russification of ethnic minorities within the USSR such as the Koreans, Tartars, Chechens, etc, would help making the USSR under Stalin a less awful place compared to OTL.
Again... In order to make Stalin even into a 'benevolent despot', we will need to change his personality and worldview so much to the point that we might as well either create an original character who managed to rise within the Bolshevik movement... Or have someone else ISOT/mindswap into Stalin, with perhaps 1927 being the best time for such a swap to take place, as it would be right after
Trotsky and his supporters got purged, hence ensuring Stalin's hold on power, but at the same time, but before the really damaging actions such as mass collectivisation and the Great Terror took place. Allowing for perhaps a continuation of the NEP; And the more freedoms for the artists and intellectuals, without the state-mandated Socialist Realism art style being imposed, allowing for the Russian avant-garde movement to continue, giving the USSR more vitality and soft power.
But again, even in such a case, our Not!Stalin will still not be 'wholesome', as the USSR will still be a repressive dictatorship.