The original T-34 could have matched the Sherman (better gun, lesser armour and superior mobility), the 85 version was upgunned and armoured so that the Sherman would feel like it was facing a Panther. But unlike previously, there would be hundreds of these tanks (in fact they would be as numerous as the Allied tanks).

But the Allies had training on their side.
If you look at the battles in Lorraine between Allies Shermans (and some Tank Destroyers) and German Panthers you will se that the Allied tankers were simply better educated. That would be a huge advantage when facing the horribly trained Russian tankcrews.
But I think it would have been a rude shock for the Allies to fight the Russians.