RE: ProX 260 .90
It might need a millimeter or two shaved out to fit, but I also want the mount to reach around to the engine mounting holes, because fast tight 3D moves stress the mount alot from the gyroscopic resistance from the prop. I think I could just bolt a thick layer of ply in there like you said. I will be using a 4258 500kv motor, a 5000mah 6s lipo, and a 100A HK ESC. (one of the few conversions that costs less than buying an engine).