Just a guess, but the way the engine is offset, way bunch, I'd say they ran the original drive shaft back as far as it would go, then, as it then became a 90 degree drive, mounted sprockets to the original hub, which would already be about a 6-8 to one reduction, so the sprockets would have to be pretty small, at least another 2 to 1 to get any kind of rpm's out of it, again, a big challenge, with little reward! Bob