I'm finishing up on mine right now - kinda peeved I didn't wait for the sale. Oh, well. I'm installing a Magnum 1.20 FS I already have lying around.

I know of two guys flying Spacewalker with 61FX. They both flew very nice indeed. Seems like the engine had the power for general aerobatics, though one guy said he flies around mostly near full throttle and wish he had more power (don't we all). Both had to put a bunch of lead in the nose (10Oz.?), but this is just the way this plane comes out.

If I were to go with 2stroke, I would probably go with at least a .90, since it doesn't cost that much more than a .60. Have fun putting it together.