sell the ZA50 and buy an AV10 OR sell the 50v frame, and buy a puch frame. none of this makes a lot of sense on a bike that has a motor readily available for it, and a motor that has a frame readily available for it.
honestly the motor mounts would take more work than it's worth, and if you figure it out....a lot of people would ask you "WHY" PLUS an av10 is pretty much going to kick the shit out of a za50. top end, low end...middle end. back end, front end...any end. stock the av10 is just faster and torqueir, and generally faster all around.
a za50 would probably snap in HALF if you dropped that kind of gear on there. RPM increase and all.unless you rebuild the crap out of it. this then...makes it too expensive and pointless, which brings me back to the point of selling/trading it to someone with a moby motor.