If you really like the GP stuff you might give there Cap 232 a try. I have one with an OS 70 FS in it and it flys great. If I was going to want unlimited power I would put the OS 91 4 stroke in it. the 70 does pull it vertically forever but it does slow down quite a bit. Mine came in at 5.75 LBS with about 1/2 a tank of gas. This is a sweet flying plane and has all the throw you could ever want.

The 70 and the 91 weight about the same and the plane will balance perfectly with either engine installed.

Phil (Mesa, AZ)