With your two engines you should only consider the 40 size.

It is actually quite large, (huge wing) and it is long. I have an OS .91 4-stroke on mine (40 size) which is about right. I think you actually need a larger engine than what you have, but if you are just a sport flier one of them would be fine to start with. Definately beef up the landing gear area if you haven't read the huge threads on these two planes.