Exhaust manifold stuck to the head

[67CC]

Had the same problem. Tried PB Blaster, Kroil, the freezing stuff, fancy tools for getting off rounded bolt heads, without success. Think there was two of them too. Don't feel bad. Someone once said exhaust manifold bolts are the hardest job on a car. I believe it. Took me three weeks.
There are only six. You need heat. Forget map gas. Oxy-acetylene until they are bright orange. Then I was able to get them out with a vice grips. Focus heat on the manifold only, not the head.