Looks like a fun machine. I think a stronger transaxle would be a good idea if they plan to use that bed or trailer hitch much. *edit* Actually, looking at the hood & opposed twin... that machine may have started life as a Murray GT, with a Peerless 820. If that's the case, it's plenty strong.
Cool find. I like it. I wanted to do something similar with my tractor. Shucks adding an ATV front end and suspension to that thing would be a cinch since the engines in the back. OK who want's to try this idea??