I faced a similar problem several years ago with my ‘46 project. The PO had reportedly taught paint and body work at a votec. The truck was worked on by his students. The body work was reported by his widow to have been mostly completed and the sheet metal primed. I was thinking some sanding and new primer coat would make it an easy and fast completion. Some of the guys here cautioned me to not trust the quality of the previous work. Reluctantly I followed their wisdom. They were absolutely correct! The previous work was a testimony to the art of plastic sculpture. That plastic junk was discovered to be almost an inch thick in places when the body shop took everything down to bare metal. Sheet metal patches in some places were riveted in place and plastered over. Really glad I listened to the guys here.