Hi, I have put together a CMpro Spitfire ( same as GSP ) with 31cc ryobi conversion. Flys great at just over half throttle. Probably equivalent to a G-23. I'm running a 16*10 3 blade MA taching at 7600. This gives about 13-14 lbs on a fish scale. Plane in this form weights about 13 lbs. Ryobi with the rear carb fits totally in the cowl. Carby fits through the firewall. These planes require nose weight anyway so the ryobi works well. And nice and cheap to run. Engine weights about 3 1/2 lbs running on the magneto. One thing you need to look at is the retract rails in the wing. There's just no glue holding them in. Reinforce them with some epoxy or similar. Both mine broke out on initial flights with reasonable landings. They weren't perfect but I wouldn't have expected to see the complete retract break out. The other thing is the push rods to the elevator and rudder. They need to be encapsulated somewhere in the centre section of the rear fuselage to stop the rods from being able to move sideways. The CM pro Spitfire ended up with flutter on the elevator due to the sideways movement, which broke the servo arm, the plane ending up in a screaming heap. Not pretty. Anyway here's some pics.

Cheers from the Land Down Under. Tim.