If your spars are warped slightly, pin the spar so it matches my ridiculous little drawing. This will build the warp out of the wing. Do not assemble the spars so the bends the same way. This will build a warp into the wing.-BAD THING!

I'm thinking that the GP 40 size mechanical retracts ought work very well and hold up better with your airplane. The Dave Browns are kinda' obsolete and hard to come by. Not very difficult to install.

Your radio should work just fine for this.

My preference is the Hitec 180 degree retract servo.

Brian