No, not as a straight replacement anyway. Not only would it remove a unit completely from the game as there is no point in getting t34/76 if you have straight access to t34/85s, the 800hp pool is too unbalancing early on due to easily being able to brute force through antitank guns with it. If I were to add them I'd require both T3 and T4 for them.
I am sorry but is there currently a point in getting T-34/76 to begin with that I am not realizing? People in my experience either have a doctrine with T-34/85, IS-2, KV-1 or ISU-152, and at none of those cases do they bother to get T3 in order to get a T-34/76 that is worse than Panzer IV in everything. It has 800 hp as opposed to 640, how many more AT gun shots can it take thanks to that? One?
It has worse veterancy. Panzer IV gets a useful ability at Vet 1 and armor at vet 2 on top of its already superior starting armor. And then you have Panzerschreck infantry covering Panzer IV, and the MG upgrade to go on the Panzer IV.
I say that creates a fair balance where T-34/85 is the better tank in raw stats while Panzer IV still has something going for it. What is it that currently justifies T-34/76's existence? What is it good for? Its existence makes as much sense as giving Ostheer a snub nose Panzer IV and making the long 75mm doctrinal. If that sounds stupid, then what do you make of the current T-34/76? If you can, you could try repurposing the T-34/76 into a command tank, and doctrines that bring in T-34/85 would bring a command 76 instead. Ostheer has a similar thing and it works. You don't lose the model, you add variety, Soviet T3 no longer sucks, Soviets actually have something non-doctrinal to hang on. It's a win win.