As for throttling the Wasps, I had this idea: Take a long piece of music wire and wrap and solder "L" shaped pieces of wire onto it with the same spacing as the engines. What you have is like an aileron torque rod with six posts sticking up off of it. These posts connect to the throttle arms on the engines. The end of the long wire is bent at 90 degrees just like an aileron torque rod and connects to the throttle servo.

So, one throttle servo controls all the carbs together off of this single, long torque rod. It could be run through the wing. Picture the way an aileron torque rod actuates an aileron, but, instead of the wire inserted into the LE of the aileron, you have six extensions coming off the rod connected to the carbs.