Need more info are you trying to treat new seams or old ones? If they are new I always spray weldable primer between the panels before I weld them. If it's old seams I use seam sealer on them after removing any old seam sealer. But thats all I got
Factory seams. Really solid car. This car will not need any panel replacements. Just a few patches here and there, but nothing that would warrant new metal.
A good example would be where the quarters are tacked to the outer wheel houses. There was light surface rust (no pitting) on the visible side of both panels. I can only assume that the same is inside the seam.