Hey Time Bandit ... I am a lover of the Hobbico Flyzone J-3 Cub. What I did was only to swap out the Brushed Motor for a Hobbycity Brushless 380 motor that cost me $26.29 which included shipping. With that motor and a lipo battery, it changed the Cub to some kind of Extreme Cub. I have included a short video of the power. I didn't need to do any reinforcing to the plane. Also, the plane become very acrobatic and zippy with the motor. But whatever you decide to do hope your happy with aircraft.

http://www.youtube.com/watch?v=WD6ApoUN14A