As I understand it, the proper procedure would be to first check/lap the bearing surfaces of the bolt lugs to ensure equal distribution of load within the receiver. If you still have a headspace problem after that, you'd then use a pull through finish reamer with the stripped bolt until the bolt just closes on a GO gauge. Some say you can use the reamer as a go gauge, but why take that chance?

When you use the reamer, it is vitally important to keep is well lubricated and chip free. You don't want an accumulation of chips to build up and cause the reamer to cut unevenly or score the chamber.

The other thing to bear in mind (and it was mentioned earlier) is that a pull through reamer is only designed to cut at the shoulder and throat. If there are problems in the middle or rear of the chamber, the reamer won't do anything to sort them out. For that you'd need to pull the barrel and use a conventional reamer.