I don’t want to throw cold water on your hopes and dreams, but you may be chasing your tail on this one. With the frame and back of the cab that far chowdered with rust, the rest of the underpinnings are likely the same.
It might be a good financial move, and be more satisfying to look around for an AD driver that is in decent shape, that you can futz around with and enjoy while you’re doing it. This is just my opinion, and everybody has one. I’ve chased that rabbit myself, and have then gotten so far down the hole it’s hard (impossible) to recover.
