If you wanted a better chance at a positive ID, you could remove the engine to see the whole bare frame, get some measurements of the frame (even lay down a tape measure along the length, width, etc then take photos with the tape in the shot), get some better photos of the overall length, side views, quarter views and do it in direct sunlight.
It definitely has some Rupp, Rupp Lancer, Dart Kart or Bug (Engineering) looks or just resembles other vintage karts from the 1960's.
I think it looks like a genuine Go-Kart 1200 (but what do I know?) but they all started to blend together after a while as the most efficient designs got copied and rehashed. Got any more history on the kart? That Chinese 212cc engine is basically sacrilege on such a kart. ...
