1955 Series 2 Chevy truck. The top of both front and rear windows have significant rust-through. Front is a lot worse, I could conceivable weld up the rear. Lower rear corners rusted horribly as expected. Lower bottom or rear also kind of bad. It's a small back window and if I have to replace a lot then I'm going to convert to big back window... Front/side airbox corners and the floor both swiss cheese but mostly intact.

My plan:
Replace both inner and outer roof panels, replace inner and outer rear, replace corners of front of floor, replace front/side airbox (is there a name for this?)

My question:
Is there a specific order I should do things? On other projects the lessens are all start at the bottom and work your way up, if the floor isn't square/true/etc then nothing will be. Does that apply here? I presume I don't want the back and roof both off at the same time for structural reasons.

Opinions?