Ford Mustang 1966 restoration re: Starter ring gear

On this 66 car. The original automatic 289 engine was replaced with a high performance 289. The starter ring gear has 160 teeth. The starter which is for an automatic transmission seems to grind on the ring gear and not engauge fully with the ring gear. We put in a spacer 1/8" which helps but still get a screetch at start up, like the bendix is still hitting the ring gear.

We are on the 2nd bendix as the teeth are also getting ground down on the front edge like they are not fully engauguing with the ring gear. It seems like the teeth on the 2 gears are not meshing correctly.

My question is for a 1966 should the ring gear be 160 or 157 tooth. If it is supposed to be 157 tooth, can we find a bendix to fit the 160 tooth gear we have instead of changing the ring gear.

Many thanks for any direction here.

Woodly