When you had the 14X4 prop on it and you heard it over revving with your mark one ear ball how did it run? Was it over heating? Some prop makes and sizes make different sounds so you really can't go by the noise being made. Needle settings are done differently from engine to engine but factory settings are usually pretty close but can change a lot depending on the fuel mix. Using FAI fuel usually means having the needles open a bit more then normal. Usuing FAI fuel usually makes the engines run cooler. You may want to tune your engine with a tach to see what you are really getting in the way of RPMs.