It would be easier to balance the Heavy Tanks if they were all available as Stock units and were available as super end game units like the super units in Dawn of War 2.
One of the biggest problems with COH2 in regards to heavy tanks was always the timing. It just didn't feel good getting a T-34/Panzer 4 and then like 2 minutes later your enemy who skipped out on making vehicles can call in Heavy Tanks.
Like the Pershing for example which was nerfed into the ground, I had no issue with it being great at killing Infantry, the problem was that it would come out way too soon, and then rather than fixing the core issue units will often get hit with triple or quadruple nerfs making them worthless.
So by having all Heavy Tanks stock, making them all available at 12-14CP and having them balanced against each other (Like IS-2 vs Tiger) would go a long way to creating a healthier Meta.
Now lets say we add in Ammo Switching to all Heavy Tanks like the Sherman, you can then adjust the range of the AP/HE rounds to further tweak the units as well.
A tiger for example could have 60 range while using AP rounds, (which would help break up the tank destroyer spam meta) but then being extremely exposed with HE rounds and being limited to 40 range creating strengths and weaknesses for each Heavy instead of the Generic attack move kill everything low risk high reward beasts that they were before.
stock heavy tanks would lead to a tech rush gameplay and who gets heavy first and we would see heavies literally every single game.
look at suprem commander for example