I've used a couple of Poulans--54cc. They run fine.

I've got a NIB powerhead for a Makita DCS7000 chainsaw. It's a couple of years old, but only factory tested. Basically, it's been started once or twice at the factory. Never even touched a log or stick. It's 70cc--approx. 4 cubic inch displacement.

PM me if you are interested in buying it.