RE: WHAT ENGINE IS THIS
Actually, though mine looks like it will be easy to convert, I haven't converted it yet. That is why I said it "probably" will make a good conversion. As Ranger Bob said; gaskets can be easily made. I don't really know about parts supply. I had a link to someone that was running, selling, and providing service and parts for the engine, but I lost the link. It was someone using them on scooters I believe. He also had a kit to increase the displacement.
Try a search on Google and see what comes up.
AV8TOR