How about something along this line:
ordinary AK receiver and rails
custom front trunnion with hole for guide rod.
custom bolt - you could saw the slots in the sides, or mill steps in a second piece and bolt or weld it together
AK firing pin, extractor
press barrel in so it lines up with the magazine feed lips, as needed
In my sketches of a "mostly homebuilt blowback AK" I always run into trouble with the top cover, RSB, GB, and handguard bits. The AK stuff is complex since Kalashnikov wanted everything to come off without tools for cleaning; if you can simplify things it would be easier to build.