You need to find out how many oz of torque each servo should have. Somewhere in the instructions it should provide that information.

You should check out the products at Bals Products http://www.balsapr.com/ The Blue Bird servos are very good.

I use the 308 MG in my Freedom 3D. The Freedom 3D uses a Mega motor, 6:1 gear box, 16x8 prop and flies on a 10 cell 3300 mah nimh pack. Performance is almost the same as a 40 size glow powered plane.

I don't think you will need servos as powerful as mine (50 oz @ 4.8 volts). I am not familiar with your plane, but you will probably want servos in the 25 oz range - Blue Bird 308 or GWS BP 106 or 107.

Someone in the electric forum or over at E-Zone http://www.ezonemag.com/ can provide more precise information.