I'm no help. Aussie stuff I use has 157 or 160 teeth flywheels, and starters which differ form US cars.
Chevies use a 5/32 wire test, if I recal properly, for seting starter position. Very simple to adjust. Shove a wire between the teath, and shim till it fits snug.
With Fords little I6's, I believe they went to adjustmnet on the starter bush itself. I'd pull the inspection cover, and shine a light, shove it in neutral, and have someone turn the engine with a shifter or ~3/4 socket anti clockwise so you don't loosen the balancer pully. If the teeth are crazed, then its a flywheel/flexplate change. There could be run-out in the flywheel, or you could have the wrong starter.
I rembember doing a wheel bearing in an Austin America. Put it in backwards. Beacuse the previous owner put his new wheel bearing in backwards. Check the part number for the year, and see if theres a mismatch. Sixes have a few different flywheel sizes, with dirrent teeth counts, altough the pitch remains similar.