To do this project, I used some scrap pipe, an old propane bottle, and a couple of gate valves and constructed this simple vapor carburetor for under $15.
With a shorter propane bottle and a air filter, this could actually be a useable system. Something tells me this design won't gunk up like the stock carb did.
This carburetor is ultimately going to be used as part of a wood gasifier. This engine is rated for 6.75 hp on gasoline, so I should still get decent power running on wood gas. The plan is to use it in combination with a alternator, battery, and inverter to produce electricity from wood.