I converted the smaller OS Gemini 160 to gasoline in a different thread here on RCU and it has been a fantastic success. You can see that thread here:
OS Gemini Twin Rear Walbro Gas Conversion
I bought this 50cc engine a year or so back specifically to convert as well. It appears to be in great shape with the exception that a previous owner put plier marks on the prop driver (I can't fathom doing that to this jewel of an engine) and one of the exhaust tubes is damaged. But a brief examination looks VERY promising:
