If you merge a Carabine M1 and a Thompson, do you get a US MP44?
Carlos, I like the look of your Thompson/M1 carbine hybrid. That said, the .30 Carbine and 7.92 kurz rounds have very different performances. In modern terms, the MP44 is an assault rifle, but the M1 more of a Personal Defence Weapon for non-infanteers.
With a weak cartridge like the carbine's, there isn't much muzzle climb. So, unlike the MP44, you really don't need to raise the buttstock to compensate. If for some other reason you just want that inline stock look, you'd need to raise both fore and rear sights.
Also, your weapon shows two cocking levers. You only need one. I'd just stick with the M1 operating slide handle - directly above the magazine - and ditch the Thompson's receiver-side cocking handle.
Still, a cool notion. I like the idea of a modernized M1 carbine