im not really sure what the best way to do that is. I would try really hard to get them out before cutting/drilling/grinding. if the head is completely stripped a smallish pipe wrench or a good pair of vise grips may get a good enough grip, try and find a pipe that will fit over the handle to give you more leverage. the tip of that bolt is exposed behind the heat sheild, so try to some PB blaster in there heat can go a long way as well if you have a little benzene torch or something.