There was no evidence of welting between the fenders and the running boards on my '38 when I took it apart but who knows how many times it had been disassembled previously. It had been painted at least 4 different colors over its earlier life.
Greg do you have the stainless that goes around the perimeter? If not, I have a couple of beat up ones hanging in the garage. A few nights with my trim hammer and dolly and they might clean up pretty well.