[blykins]

The first plan of action is to find out why you lost the teeth...

What engine, bellhousing, starter, and flywheel?

If you can provide answers to those questions, it will give us a little more information to go by.

If there are no reasons why these particular parts are not compatible, then it could be possible to just replace the ring gear on the flywheel.

I suspect there's an underlying cause though....