Hi!

I have the World Mdel Cap 232 with a Saito 72. Presently the c.g. is positioned at 95 mm, which I have found to be a good compromise for my flying style (traditional aerobatics). IMHO the manufacturers value of 83 mm is on the conservative side, 100 mm on the other hand is too far back unless hovering is your only interest ;-).

The WM Cap is one sweet aircraft to fly. It is not ideal for 3D, but flies IMAC style aerobatics very well.

Using my old JR-388s Tx my set-up includes:

15% aileron differential
+12% left rudder to elevator mix (elevators move up with rudder input)
+15% right rudder to elevator mix

The rudder-elevator mix is to correct for the usual tendency of CAPs to tuck towards the belly in knife-edge flight.

I suggest you start with about 2/3 of the recommended elevator throw to start with, i.e., approx +- 25 mm.
Later on, when you get accustomed to the aircraft you can increase the throw. On my aircraft I have set the elevator throw to 30 mm up and 35 mm down in order for the aircraft to perform inverted and upright loops of equal size.

BTW, while the APC 12.25x3.75 (and the 14x4) propeller is good for 3D hovering, IMHO it is about useless for anyting else. With your engine I would try an APC 12x6 or 12x7 propeller in order to increase the level speed, thus facilitating large looping maneuvers.