I built a Contender some years back, I really went all out on it and mounted the engine inverted, cowled it in made a Navy color scheme with a great pilot. I powered it with an OS max 45 FSR, plenty of power!! flew fast and was fun to land. I think a good 45 or 46 engine is plenty. One thing that will blow you away is, Averse Yaw on the rudder. You give left rudder and the fuselage tilts to the left but the airplane rolls to the right!!! no biggie really. The plane flys great! Have fun!!! I dont recommend going to all the trouble of an inverted mount tho. just my opinion, looked cool but lotsa work.