Hello; Well just jump on in, pick one you like, it's hard to make a mistake nowadays. Anything in that size will likely be easy to run with a shallow learning curve. My personal choice would be an OS 91 Surpass, but then I'm partial to four strokes. Or a Saito 72. Start em early on 4 strokes and they'll never suffer the two stroke (ah-hem) experience. I flew tow of my planes today, a 30 Saito powered pixie biplane, and a Laser powered Taube. A very pleasant day. Other people might recommend other engines, but it is true that it is hard to buy a stinker these days.