Have you tried heat on the wheels? Maybe just run a torch around the wheel for a minute or so, then give it a smack. Might be enough expansion to bust it loose.
When we took the rearend out of my step-daughters '65, I cut the u-bolts with a grinder, and a sawzall. Make sure you cut them close to the top of the "U". If you don't, you will get to cut them again.
That is the voice of experience on that!!
Luckily I only did that on one of them.