Ditto to what Barry and Gary have said. The Saito 82 works perfect in the 46 size if you can get one of those that would be a great match and I think would be your best bet for performance and fun. Save the 72 for something else.
The U Can Do are an awesome plane. You'll have more fun with it than you could imagine. I've built and flown several planes since my U C D but keep coming back to it. The 46 thread is long but if come over to it you get all kinds of info there without having to read the whole thing, just ask what ever questions you have on there and you'll get all kinds of info. [8D]