I have a Saito 180 in mine and I like the combination. The perfect engine for this plane will weigh about 2-2.5lbs with muffler to avoid adding nose weight and not be lacking in horse power. Based on the prop recommendations for the Saito 180 and the O.S. 160., the 160 may be a tiny bit more powerful than the 180. I haven't flown a plane that I wished had less power and more lead ballast, so I think the 160 should be a good combination for the Great Planes Gee Bee.