Why not implement something that is already in the game?
I remember the campaign had units called Frontowiki squads. They are basically buffed cons with ppsh and ai nades.
My suggestion would be to give cons the option to upgrade to these Frontowiki squads once they reach vet 3. For a small manpower and munitions price + t3 or t4 researched .
By this the Soviet faction manage to scale their cons well into the late game. It would support combined arms because you'd still need 1-2 cons squads for at nades and sandbags.
And fanboys would get their battle hardened core infantry that has a better name than conscripts.
I think this idea is extremely interesting. Upgrading a unit to become something else or have a slightly different role. If you upgrade the 221, it becomes a 222. Im not sure about a vet requirement, but it would be nice if cons can do more and fight better once you get t3 or t4 (asides of the lack of flexibility within t3 or t4 compared to other things). At this point in the game, PPSH's being only doctrinal is trivial.
As for the Soviet faction, i have been on an Axis/slightly American vacation for 4 months now. They are too lacking in originality and flavor compared to WFA factions.