Ever thought of a chainsaw conversion?

You could get a Poulan Pro 260 (42cc) for the plane.

For it's size and class-- the MVVS 2.15 is kinda heavy and a little low on grunt. Thats just what I read in engine specs and forums around the web. I have no personal experience with it.

The Poulan Pro 260 (42cc) is said to be stronger than some 44 and 46 engines. It's pretty light too.

You can get a Poulan Pro 260 from Ken Lambert for a nice price-- compared to the MVVS 2.15. The NIB MVVS 2.15 is gonna run you around $400.

Just a thought.