Ditto what David said. I've done the same thing. I used a Williams Brother's pilot, a wooden dowel glued to the head thru a hole I drilled thru the bottom of the head and the center of the bust where the head rests. The dowel is inserted thru a hole drilled into the cockpit floor under the bust. Just beneath the floor, I glued a servo arm, of which the center hole is reamed out to the diameter of the dowel, to the dowel itself.

Once the pilot bust is glued to the cockpit floor, the dowel doesn't move laterally, only radially about its center. I attached the rudder servo arm to the bust's servo arm with a pushrod and clevises. Works like a charm!

Good luck with it.