I'm glad to see you considering everything when you talk about engines, very impressive. It all must be counted including the fuel. It was hard to believe that the feather weight Saito 180 was the same weight as the RCS 140 gasser including fuel but the Saito 180 easily needs a 24 ounce tank. Also consider that with the "pumped" gas engine you can put your tank on the CG. The plane flies way better with the tank there.

I have a CAP232 120 (see my avatar) and I use the Hitec 5645's all around. They are great servos for 47-50 bucks each. Use a 6 volt battery and you have 168 oz-in per surface. These servos will hold any position on any manuever with that plane.