I would agree on the 40 size 2 stroke. A Thunder Tiger 40 or better yet 45 pro would work well. But I guess I will admit to being the original wierdo. My first trainer was a PT-40 with a Saito 45s. I learned with the little 4 banger. It had plenty of power for this plane. And yes I did dork it and damage the engine. I still haven't got around to sending it out and getting it repaired. I would say the 65 (which is a great engine BTW) would be way too much. And a little too heavy to get it to balance right. If you must 65 then you must. But I would go with an inexpensive 45 2 stroker and have a good time with it. Good luck whichever way you go.

Mark Shuman