PB Blaster and let it sit. Keep soaking everything down for a few days then try the vice grips. I've had to drill a few. If you have a small torch you can warm the bolts a few times... that might help.
I spent a week, used heat, mixed concoctions, tried every tool in the arsenal, and a few other methods to loosen 12 head bolts on a 787. I also damaged a few tools and managed to get 10 of the 12. No cigar, I still had to cut the head up to get the bolts out. Be gentle till gentle don't work no more. LOL Good Luck !!