Wow... I admit I've not read all the responses here, but I'll throw out a variation that a friend of mine used to use when he had a stripped nut. He'd take his mig welder and add a blob to one side of the nut and then use some vice grips to torque it off. You sound well past this point.

I've removed these same bolts many times with just a 1/2" drive 2' breaker-bar and a standard socket. Something's wrong here to cause you this much grief...

One thought is that you should heat that bolt up with a torch and then cool it quickly. It will ruin the temper, but the bolt with swell slightly when hot, and shrink when cooled and this may break the friction holding in place. I think this is suggested in the BB 700/900 FAQ.

I do have an idea to get you around that stripped bolt head and my suggestion comes from the problem I usually have with the really big nut that secures the cam.

Until I finally picked up a 1 7/16" 3/4-drive socket, I used a very big old-time PIPE WRENCH. Those will bite into anything, even stripped steel.

To get the leverage I needed to break that nut loose, I'd remove the wooden wrench handle and use a 1.5" diameter 6' steel pipe slipped over the steel shank of the wrench. Massive leverage and massive biting power. This has worked EVERY time I've needed it. It has yet to fail me.

If the pipe-wrench does fail you, you might as well give up and drill that baby out, because it is simply not coming back out.

Note: because of the damage the wrench will do to the nut/bolt head, I do not recommend it for every-day work, but it is a good tool to have for last-resort problems.