[Tom Wesenberg]

Unless the studs are severely pitted, I'd leave them alone. If they must be removed, then I'd use an ox/acc torch to heat them red hot in the area next to the block, and as they cool spray some penetrating oil on the threads. Repeat a few times then try to remove them. Instead of penetrating oil, I've heard good results using wax to soak into the threads.

If or when they break, then Vince has an excellent way to remove the broken part by welding on a large flat washer and nut. This has never failed to work for me.