A Saito or similiar 120 will fly a 14 pound warbird without problem. If you have a need for speed or want to 3D it then put more power in the plane.
A Laser 120 similiar to Saito 100 will fly the CMP 70" 11 pound Zero well with a 15x6 APC at 8.3k sealevel. I used a Saito 180 in a 83" 17.5 pound Claude and it flew very well.

Decide how you want it to fly and pick your motor acordingly.

Carl