I just finished converting a medalist. I cut two slots down each side of the bolt cutout with the round flat cutoff wheels, then made a cut down the center to the same depth. Then I used the smaller( 3/8 th's) in sanding drum to hog out the notch. it come out great with very clean sides. I did end up cutting it a little deep which was no problem I just used a little bit of the JB weld that I filled the other bolt notch with to bring it back to where I wanted it.

BTW I am still sitting on a converted long action Duramax that I got stuck with. I would make someone here a real good deal on it.