I'm not sure about the performance with a magnum but I saw one fly with a saito 30, it wasn't gonna set and speed records but I thought it was a pretty nice combo. People who know me know that i would put a Da-150 on the thing hahahahahaha. But it depends on how you fly. you could even put on a piper cub.

http://www.towerhobbies.com/listings/cat-cat-a.html
Go here they have some pretty small planes.

Keep us posted on what you decide. Thanks