This is interesting... a 100ci 60HP (claimed) engine using two cylinders from a Continental O-200 and other components:
Introducing the Pegasus Power O-100 Light Sport Aircraft Engine
At $2500 for the new parts plus you still have to buy the O-200 parts it might be a pricey alternative to, say, the HKS. Or it might be cheaper; I have no idea what Continental parts run these days.
The single web page is lacking details, though, and the engine picture is an "artist conception" though...
Be wary of strong drink. It can make you shoot at tax collectors-- and miss.