The first thing you need to do is make sure the index hole for the nose of the starter is not broken in the bell housing. Next I would look at the flywheel and see where it is rubbing, the starter could be in too deep and rubbing the face off the flywheel, a sheet metal shim will fix that. If the teeth are too close to the flywheel your only choice is to grind a little off the side of the starter nose so it can move over about .020, or dial in the bellhousing to the center of the crank. The factory bell can be a little funny with that starter, have seen guys bust the nose off when they tighten the bolts without the shim, I know it works perfect most of the time, sometimes not.