Check on vintage kart forums or search just Power Products AH81 engine. They aren't an especially rare powerplant. The manifolds from the carb into the case should be fairly easy to come by. The elbow in front of the carb, if you are comfortable with brazing or welding, could probably be...
It has the Schrader at the bottom, but I don't remember what adapters came with it. It's been in a drawer under the Actron one and I haven't pulled out in probably 4 years. I'll have to drag it out when I get home tonight.
Partner versions of this powerhead were sold in limited numbers as a cutoff saw. If you have an old construction equipment dealer local, see what they have.
5 years ago it seemed like everything was going to FB, YT, Twitter, Instagram, but in the the last year the editorial hands on those platforms have laid heavily enough to chase me, and others, back to the enthusiast specialty sites on the wider web.