Have you run the specs of the plane through MotoCalc ? Motocalc will put you IN THE GENERAL BALLPARK as far as motor type/size (and/or gearbox_, prop, and battery. If you go to the opinion section, I have found it to be pretty accurate as far as performance is concerned. FWIW - Motocalc has a free D/L with a 30 day full function trial period.

The other way you can do a setup for electric is to take a READY TO FLY WEIGHT for a glow setup, then use the following to determine the size motor you will need:

60 - 90 watts per lb = barely flyable to trainer type flying
100 - 150 watts per lb = general sport flying and mild aerobatics
150 - 250 watts per lb = aerobatics and MANY SCALE warbirds
250 - 300+ watts per lb = 3D
450+watts per lb = wings are optional {:-)

These figures are approximations and will vary by wing area/type of plane. For instance, a SCALE 5lb Piper Cub will fly reasonably well on a 300 - 350 watt motor, but a SCALE 5lb P-40 warbird is going to need about a 700+++ watt motor to fly.

This is MUCH LESS ACCURATE, but it will still put you in the ballpark as far as the motor is concerned - you just have to do more work selecting the specific motor, battery, prop, etc.