Don't you dare touch rapid conscription.
Also Soviets are strong.
Penal troops are good enough for their cost.
Cons don't need DPs.
M3 is fine.
T34/76 is fine as a main battle tank; just needs slightly better machine guns.
Su85 is fine.
Hit the dirt indeed shitty and the B4 has too much scatter, those are about the only things I would change.
Cost of the penals close to rifleman and IS (270 and 280), but their firepower and functionality much lower.
What about T4 (T-34 and SU-85)? I don't see the reason to build it. SU-76 is more cost effective and provides protection against all vechicles, except Elefant and Jagdtiger.
I find reason to build T4 only when T-34 be in a line with M4A3 and Cromwell and SU-85 will be in a line with M36 and Firefly.
Now i don't see reason to spend money on them. They are useless, their cheapness is not the argument.