I've seen the same claims of 'out a tooth' and always wondered how that was determined. Seems to me if the timing marks are lined up and the distributor is slipped in so that the rotor lines up with the appropriate spark wire on the cap... just doesn't seem to be much debate. It either is or isn't. I guess the big question is does the rotor line up just before the cap contact, or dead center. I know when I rebuilt my head I ran out of turn before I could get the timing right, so I pulled the distributor and carefull wiggled the rotor until I felt it engage one tooth back and put it back together. I was able to get the timing right at that point but there was nothing scientific about it. To the eye the rotor didn't line up with the mark I made on the distributor.