Very rusty rear coil spring bolts in 1968 C10

[HeavyHauler]

I had began putting WD40 and PB blaster several times on the rear coil spring bolts for my 1968 Chevy C10 multiple times over several months this past summer because I knew that I was going to be working on the suspension this winter. Well I finally started trying to remove them today and those bolts are simply not moving a inch. I also tried heating them up and removing them with a small bernzomatic propane torch but they are just frozen in place.

I was trying to save the rear springs and not have to cut and damage them but it seems I have no choice. I am wanting to install some lowering coil springs.

Anybody with any other suggestions on how to remove the rear coil springs without damaging them?