I fly quite a few older engines, mostly Quadra with magneto. I use regular 72 MHz FM radio and have never had any interference problems. I do use a non conductive throttle pushrod (usually nylon) and make sure I have no metal to metal items on the model that can rub together or vibrate. I find it difficult to keep 12 inches between receiver and engine, most of mine are probably in the 8 inch range with the battery and associated wiring right behind the engine and no problems in the last 15 years of gasoline flying. I do keep thing separated as far as possible though to minimize the possibility of problems with RF. Be sure to use a resistor type plug. If the part number has an R in it, it most probably a resistor plug. Keep you kill switch wiring in front of the firewall. In answer to "do you have to use a separate receiver and ignition battery", the answer is YES.