But clearly Stalin was certainly ready to begin expanding the Soviet Union, once he felt strong enough. ==
Yeah yeah. And Stalin was bad enough that he eated alive orfans on breakfast.
As I said that Stalin already dead and he is enough bad person so you may not demonize him ever further.
I know it is politcorrrectness to demonize Stalin further. But still it is like to "kick dead lion". He is already dead so can't bite you.
The Soviet Union never abandoned its long range goal of world domination, the only question was a tactical one of how to achieve this.