When I used to mess with the FWD stuff (lot's of torque to yield stuff there), the rule I remember was if there wasn't any necked down areas on the bolt, it was ok to re-use them. I always bought new head bolts (I think), but it seems like there were other bolts I did re-use (maybe intake?) after checking them.
That said, I thought that most torque to yield bolts included a procedure of torquing them to a certain point and then giving them a 1/4 turn more. The instructions I have from when I put the M1 on my motor don't include anything like that. Only a bunch of steps to torque the bolts in, until they are all at 12 ft/lbs. Not say they aren't torque to yield, just saying the one source I looked at seems to indicate that they aren't.
