I've built both of the Tecumseh engines. For your application, I think an H50-60 might be the better choice because in stock form they produce oodles of torque. An HS50 doesn't cut it on a heavier bike (I have one on a Wards 525 and it strains).
Delray and I have shared notes several times on the OHH195 engines, and he's built killer motors. My OHH was a far more simple build--adjustable carb, aftermarket air cleaner and a header. My OHH easily out-pulled the two Predator powered bikes I had at the time (hemi and non, and all on CAT frames). Properly tuned, the OHH climbs smoothly up the rev range and torque is spread evenly. A caveat, though, they can be finicky and like a smaller carb (HS40-50) as opposed to a H50 carb.