I have an issue with a bolt on one of the cylinder heads on one boat
engine I have. I need to swap cylinder heads on the boats, and the
donor boat is fighting me tooth and nail.

The problem is that 1 bolt will not come off. It's towards the bottom
of the engine (I had to take off part of the engine cover part) and no
matter what I do (vice grips, socket, soak it with liquid wrench)
nothing will budge this thing.

Any suggestions? I can provide pictures to better explain where the
bolt is.