I've built a couple of the Great Planes Taylorcrafts. It's my favourite plane, and I hardly ever go to the field without it. I'd definitely recommend that one to anyone.

My first one had a Magnum .30 four stroke, and it flew very well like that. My current one has an Enya .46 four stroke, and it's overpowered. Your Magnum .25 should fly it very well.