Happy to help!
The thing with vinyl top induced rust is that the top rusts out under the vinyl. Sounds obvious, but what that really means is that the integrity of the metal can actually go away before the vinyl does. So the whole idea of there being worse damage doesn’t necessarily pan out. The vinyl will keep a lot of water out of the car even if it’s over metal with holes in it. I didn’t know how bad the roof skin on my bronze car was until I peeled the vinyl off and it took metal with it. The damage you have to the trunk pan happens all the time on cars that don’t have holes in the roof skin.
As far as learning how to do it, it may look like a daunting task, but replacing the roof skin probably requires the least amount of skill of all the repairs needed. It will take the most time because of the size of the repair. But drilling out one spot weld is the same as another. 200 takes time, but it doesn’t require any more skill than 1, or 5, or 20. And with the roof skin, all of the spot welds are hidden. Under the windshield and back window in the gutters, and under the seam sealer in the drip rail gutters. Even the roof/quarter seam was designed to be filled. So your welds don’t have to be beautiful, they just have to be solid. The edges clamp right to the hardtop structure so it’s easy to locate the roof skin, and it’s hard to warp the panel because of that structure as well. Everything is edge bound except for the quarter seam. So yeah, it takes time, patience, and labor, but not a ton of skill.
The hardest part to fix will actually be the tops of the quarters, because you’ll have a sheet metal-to-sheet metal butt weld on the quarter side of those patches. You can minimize warping by choosing the size and shape of the patch well, but you’re going to be working in the middle of a panel for part of it. And they’re only getting covered by paint and bodywork, so warping it a little has big bodywork consequences. The smallest repair area you have requires the most skill.
The way I see it, you aren’t risking much trying to fix it. The car as a whole with that damage isn’t worth much. If you part it the money will come from the mechanical stuff, the shell by itself will be hard to get more than scrap value for. If you fix it, awesome. If you start into it and do find more rust, you’re only out your time. And if you do some of the work and farm out the hard stuff, you’re still no worse off really. You can buy another car and lose out too, there’s a lot of bondo queens out there.
If you have time and patience, are even a little mechanically inclined, and are willing to take the time and practice some skills, you can tackle a lot of what you need to do.
