Take it from an oldie. Been working on cars forever, and the absolute hardest thing to fix is rust and advanced rust to the extent of body cancer. Overhauled engines, replaced trannies, and third members, but the 85 I restored for my son had a very small area of just surface rust on the rear roof. Hardly could see it. Addressed it, I thought. Had car painted and darn if it didn't show up after a few years. You seem to have a handle on how your handling the resto on your Isuzu. Been following along. Detailed work should pay off with one nice resto.