The lower sections of the front half of the B posts were repaired by fabricating small shaped panels and mig welding them in place. The back of the posts were cut away with a 3 inch air cut off wheel. I found that using a spot weld cutter was very slow and still required grinding.
The inside of the post was cleaned, primed , and painted. New backs from Moss Motors were fitted and welded in place. The seams were sealed with Fast n Firm from NAPA. I've used this seam sealer on all joints that do not flex and will not have to be taken apart again in my lifetime.