When I was working at a Honda repair shop a Prelude came in with the bolt broken and I tried to get the bolt out with an easy out and it would not budge and almost was to the pouint of breaking the easy out itself which was a #5, pretty stout one. We ended up just giving the guy the car back unfixed.

A machine shop ciould probably get it out but they won't usually toch something like that unless you brought them just the motor on a stand or something.

You may want to try heating the crank up with a torch and then spraying with PB balster let it soak then heat it up again and respray it. Do this a couple of times and then try to back the bolt off.

I don't want to sound too pessimistic but you may end up needing a new shortblock or crank.