Something like this would work fine...
Motor
[link=http://www.hobbypartz.com/mopose.html]Motor Click[/link]
Hmmm: Link's not working... cut and paste the text into the browser... don't click on the first link...
http://www.hobbypartz.com/monsterpow...ess-motor.html
A 50A ESC with UBec ( not with an SBEC or just "BEC" ) such as one of these...
[link=http://www.hobbypartz.com/60p-dye-1017-50a-esc.html]ESC - Click me![/link]
A 4S battery pack, of at least 20C 2600mAh... higher capacity if possible depending upon your plane.
And a 12x6e or 12x7e prop to go with that.
It would be helpful to know what plane you are actually converting?