Y'all know this is crazy, right?
The T3 T-70 is already so strong it appears in almost every SOV game.
The T-34/76...
...is only 20 MP 20 FU more expensive.
...has twice the armour.
...has 260 more HP.
...has twice the penetration.
...is similarly brutal against infantry.
...fires three times slower but at four times the damage.
Think this through, people. 75 FU of teching is what makes the difference between Mobile Defence being the sole meta and being on the junk heap of doctrines.
You'll break the game if you stick the T-34/76 in T3.
Make a T3.5 then, as others have suggested.