M35A2 Cab sheet metal - Spot welded areas

How does the 'new manufactured' spot welded cab sheet metal look?
Over the years rust(between sheet metal layers) has puffed up the couple inches between each spot weld.

But couldn't have looked that great brand new, from the looks of it.
What's the consensus, how far do people go in prepping this area before paint?

Depending on the weld-time and tension setting on the spotwelder and how the the weld was done; there is usually a round depression about the diameter of a pencil eraser and about .010 to .015 deep where the tips of the spotwelder pressed into the so-hot-it-was-soft sheetmetal. the rest of the surrounding area would be smooth. Hard to get in between sheetmetal layers for rust removal. I'd think in terms of getting some of the rust conversion stuff like RustMort or something similar, and try to saturate the seams.