Check out lawnstation.com for their Poulan chainsaw offerings. For around $100.00 or so you can get a 42 or 46cc saw. These are easy to convert as the engine has nothing to cut off to use for a model engine. The 46cc requires a special carb adapter available from several suppliers. The ignition is simple to do and I recommend Ch ignition. Their site is www.ch-ignitions.com. I'm in the process of ordering a 42cc for myself, because it is about the right size for my project, and nothing needs to be done about the carb mounting on that model. If you want, contact Lawnstation by phone or e-mail, and they will sell you the engine alone; without the chainsaw trappings. Price doesn't drop much this way, but you won't have parts to throw away!

Have fun,

AV8TOR