Probably still a bit below Western Europe, but likely not as far. You gotta remember these were almost all semi-feudal societies with the vast majority of the population being peasants, it's gonna take a ton to get them to the level of the West. Stalinism, for all its political faults, was good at one thing - industrialization.
While Central/Eastern Europe was behind Western Europe, it would be wrong to call it semi-feudal and imply there was no industrialization and that everyone was mainly peasants.
Czechoslovakia was highly industrialized. While Slovakia was still mainly agrarian, Bohemia and Moravia were in the same peer category as Germany and the West. Stalinism completely ruined Czech manufacturing because the "plans" for the Czech economy did not take into conisderation their high skill level and lack of certain resources.
Hungary had a strong light manufacturing sector and had a strong indutry around railways, tramcars, electrical generation, and automotives. Because of lack of natural resources, it lacked many heavy industries.
Romania didn't have as strong an industry, but it had a strong oil indutry, and its industrial production had more than doubled in the 1920s and 1930s despite the Depression. It seemed to be doing fine.
Poland had established a vast industrialization plans on its own. It included development of its own seaport at Gdynia (so it would not be reliant on Danzig), increase in railways, creation of a Central Industrial Region that greatly expanded its heavy industries, and a general attempt to reduce the disparity between western and eastern Poland.
Yugoslavia had a strong industrial economy in the north, and that pretty much remained the same all throughout the Communist period.
I think Bulgaria was the only country that still remained mainly agrarian. Still, even here Bulgaria had instituted various reforms since gaining independence from the Turks to increase education, urbanize, and reform agriculture.
Stalinism does create industrialization, but only of the most brute kind, of low quality and low skilled, and at the cost of consuming the capital of existing economy. Central/Eastern Europe would have been far better off building on real economic growth based on actual demand, and the increasing of skills.
None of these countries were as backward as Russia. They were all western oriented, and most had some kind of industrial legacy from the old Austrian-Hungarian Empire.
If allowed to develop on their own with Marshal Plan aid, and able to trade and cooperate with the West, they would probably have economies somewhere between Austria and Greece. Some might even be considered peers of countries like Belgium or Netherlands. Poland would probably be considered the most important European economy after Britain, France, Germany, and Italy.