I'd be dribbling some aerokroil around the threads of that thing now, tomorrow, and the day after when you actually attack it. dribble it in on both sides of the threads. just before you're ready to remove it, ice down the fixed cup so it as cold as you can get it, then apply mild heat (hot air gun, not blow torch) to the BB shell, try and get as much temperature differential as practical, THEN go postal on the big tools.

have you found a raleigh 26TPI threaded BB ? as several people said, the vast majority are 24T 'british' which is totally incompatible.