It has to be saved for sure. I would just weld up the roof frame where they cut through it before I did anything else. Looks to me like getting rid of the surfacr rust and cleaning everything up will be the hardest part of the job. I think people generally will put an insert inside of the A-pillar and weld both pieces to it (you would weld the insert to the bottom of the pillar first, then drop the roof down and weld the top portion to it).
