TBH, it was always dumb that the Soviets in game are the only faction without nondoctrinal SMGs. The Red Army was famous for its widespread adoption of automatic weaponry, and they have none on their stock units.
Personally, I feel like Penals or conscripts should have had PPSHs available as an upgrade stock, but since that isn't possible, I think the conscript PPSH package should be changed into a new call-in squad (call them Avtomatchiki), and have them available at 1 CP. They can keep OORAH and molotovs to make them different than shocks, and have the combined arms ability similar to panzergrens. They would not have AT grenades though. Since they would be hard countered by vehicles, they can then be buffed to be better at the AI job (and price increased accordingly).
Not sure if this would count as a "new" unit, since they would just be conscript models with smgs. If done, this would give us another unit to help make Soviet doctrines more unique.
I'd suggest the new squad can use these models: