I went a different route than most here, Mine are pretty far back to keep them away from the ignition. There are two schools of thought - 1) Ignitions are cleaner these days and no RFI problems and 2) keeping everything as far away as possible. I built a small servo tray and mounted mine behind the tank. I used a sullivan nyrod semi-flexible nyod on the throttle and a flexible one on the choke. Each with 2 anchor points as they move forward.

Since the picture, I have since changed to a standard servo for choke. The DA-50 choke is a little tough on the micro servo and it burned up. As far as balance goes - mine balanced at 7 1/4" from trailing edge of wing with no weight added.