Michael, I would suggest going with the YS 140 as it has a fuel pump built in. This plane needs one as the tank is set back over the CG. Thats alot of fuel line for a pumpless engine. I had the 73 for the past year ( until about 2 weeks ago. was begining to think I was Somenzini doing 3D very low
) and ran both the saito 180 and 220 on this plane. They both performed very well but needed a perry pump. The YS 140 is around the same power as the saito 180 (maybe even more powerful). I'm pretty sure thats the engine this plane was designed around. Good Luck....EMVIN....