I would say no---think of it this way--the sides and top are a frame that is structural. Many of the frame pieces are layered over each other--in some places three times. They go together one way and cant be taken apart without the skin being off.
The sheet metal is the skin which goes over that framework. Once you start removing the skins it becomes clear how the car went together--it would appear from the ground up--the panels above overlap the ones below.
With that being said if you cut the a-pillar and the sail panel you would be cutting in the middle of a structural member with no way to get at the back side to weld the sections back together. The a-pillars might be easy to weld back together as they are basically a "pipe" and you could weld all the way around. The sail panels would be a pita--they are two box sections joined together--the outside section would have to be welded thru the sheetmetal or cut a section out to get to the member behind. Not to mention you now have a buttweld seam where there was none before--I'd be hesitant to do it as I think your just creating a stress area where cracks are going to form. These are unibody cars--they flex enough without creating a place for them to do so. Either way is alot of work and I'd not want to see cracks in my paint. Plus it would be ALOT of measuring and cutting to make sure you take it off the same place on both cars--then line it all back up and get it back together-----not me brother lol--the openings accept doors windows etc the way they are now--I dont want to create fitment issues.
As it is right now the roof structure is still strong and put together the way it was engineered. You could stand on the roof bracing right now.
While doing it the way I did is time consuming its simply reversing the way it was put together. And when it goes back together all the areas I had to drill all the spotwelds from will be "hidden". In the windshield and back window area those will be hidden by the glass. The sail panel and the a-pillar weld areas are recessed and will be covered by lead. Much easier to finish in my opinion and make it look good.
So could it be done removing it in one piece--sure
Are there a hundred other things you could screw up and make a mess-yes
Would I do it the same way I did it again--without a doubt.
Oh another thing--The parts car roof and frames are in excellent shape--but the skin and bracing still show surface rust. Its pretty obvious all this stuff was not painted but only got the overspray from the primer and paint from the jams body etc. The stripe you can see on the roof in the background is raw steel that was sitting on top of the brace!!!! Taking off the roof gives you access you will never have again and I plan to take advantage of it and hit it all with Eastwood rust converter and encapsulator. In my lifetime I shouldnt ever need to worry about it again.
Oh and I got everything but the spotwelds over the rear window done on the car I'm fixing today
