[Gobuffalo]

I have restored a number of cars and trucks. My best advice would be not to re move the body from the frame until your finished with any panel replacement.
The procedure I have always used is to check that the frame is straight, dissemble as much as you can leaving body panels in place, do all the rust repair and body mods, then put it on the rotisserie. If your door hinges are loose rebuild or replace them before you replace any panels around them. This is the only way to insure everything fits once it's sitting back on the frame.
If you have already removed it from the frame, make sure the frame is straight, buy a new set of body mounts and place the body back on the frame.
Or you can build a jig that supports the body at the mounts. It's a lot of work for one restoration.
If you don't support the body at its mounting points correctly and you start replacing panels it will be very difficult to get everything lined up again.