McCulloch...
Yeah, stay away from the McCulloch saws. Real weird layout that won't work with a prop, and roller instead of ball bearings.
The 28/32 weedeaters are great however. Lots of power and very easy to convert. Nothing to cut off. Once you get it all unbolted out of the weedeater, it looks like a "proper" little airplane motor!!
Have fun,
AV8TOR