dont overpower it. i made that mistake with my pheonix yak 54. i put a .91 4 stroke on it and with the weight of the spinner/prop/ect i added about 3/4 of a pound worth of extra weight (and th lead to balance it). the plane flew and has insane power, but if you slowed down, it flew horrible, it just wanted to fall out of the sky.
keep it light (smaller engine) and your plane will fly sooooo much better