I think we all have had the experience of "what did I get myself into" when working on these trucks. I know in my case I was hoping for a lot less panel replacement than I am finding necessary and as you are finding, and others have reported the replacement panels are often more a source of raw material than a good fitting replacement panel. I am probably not even doing as much as I should in some areas trying to balance between building a new truck from pieces and parts and having a patched up "rust bucket" as my wife refers to my truck. As you said, once you have invested a lot of time and sweat equity into a project it is hard to back track or not coninue down the path you started on.
Keep up the good work and continue to keep us posted on your progress.