Update #2: Both rims are free. I was setting up to try some chemical rust remover and noted a gap between the rim and the hub thru one of the unused lug holes...few whacks around the rim and off it popped.

Thanks again for all the advice. Seems like clean/soak/beat rinse repeat was the answer.

Chris

Too many to work on
4 bolts, 2 square bodies, 4 GMT400s...and those are the keepers