Has anybody taken out the long hinge pin in a 29-31 hood? If so how did you do it? Thanks.

Just tap it out a little and use vise grips to slowly pull it out. Might want to use a little liquid wrench the night before. Work on a flat surface like the floor so that the tabs don't get bent.
Be careful when you paint so uou don't clog the openings that hold the hinge rod. Make sure you cleanup and lightly lubricate the hinge rod before reinstalling.

karl31 has covered the basics. Once you get the rod started enough to attach a drill, this will make removal a easy chore. Just turn slowly and pull on the drill.

I would purchase a stainless steel rod to replace the one you took out.

I am just pulling it out to get the hood to close easier. Thanks