What if Penals were in the HQ, but you had to have T1 or T2 up to build them?
Making them more accessible would fix most of their problems I think.
Or maybe take notes from US teching. For example, for T1, the only available unit is Penals, unless you upgrade, and T2, only Zis. Make them each a bit cheaper, but you can only tech T3 if you build both, or fully upgrade one.
How are you going to redesign T1? This will definitely require adding a new unit to make T1 an alternative to T2. Adding new units is impossible.
I feel like the only good option is to shift the M-42 or AT Partisans into T1, so you're not forced to go for PTRS. The Partisans come with PTRS, and you can pay munition for the stolen Schreck, similar to how AT Tommies work.