new to this thread but I thought I should chime in.... starter grinding can mean a few things. Like first post said, inspect carefully, it would be a little more relieving to see the wear evenly across the whole flywheel but often times when a bad spot happens in the motor it will stop at the bad spot more often than random and also when cranking that bad spot receives more wear than the rest. If the bad spot is very localized to under 10 teeth I would expect either a leaking injector or blown HG or crack causing coolant to be causing minor hydrolock.
If you can get it to grind, take a screwdriver / wrench (the screwdriver can fit between lugs on converter) and spin it by hand feeling for any spot that has more than regular compression.
Themn again most of these starters dont need shimming but some do and there are plenty of write-ups about proper clearance and shimming. Get that back bracket on. I am sure you went one way r another with this and hopefully have a good story