Daniel,

A good electric set up w/ lithium polymers like you requested is really a great power combination but unfortunately not cheap.

with that in mind you can go with a hacker B50 series which comes w/ a couple of gear options along with wind options. both of these are married together, so to speak, based on the performance of the specific plane you are thinking about powering. With electrics, you will be able to pick your prop size and rpm, and is best to match both of these to the specific plane for best performance.

A 3D combo I have set up is a 60-90 size conversion w/ 6S4P Lithiums, swinging a 20 x 8 prop at 5800 RPMS or so. A Hacker B50 XL w/ gear is used in this application.

You can back up and look at cheaper motors w/ offset gears and nicad batteries, but weight penalties and duration issues are some of the drawbacks.

Good luck!

Rob