[bobcowan]

As said above, you're probably going to end up pulling the motor anyway. The piston and block will be so damaged that you'll need to do some repairs there.

But sometimes it's easier to remove the engine with the top end off.

Take the nut off the stud. Unscrew the stud enough so that it is clear of the head surface. You can't remove it from the head, but that's OK. Use a binder clip or duct tape so the stud doesn't fall back in the hole. You can then separate the head from the block, and remove the head with the stud in the hole. Be sure and put the stud back in the hole before setting the head back in place.

It would probably be more difficult with a bolt in there, as the bolt head would be much larger.

Once out, you could probably shorten the stud by 1/2" on the block to make the process easier.