Then the fun part. I couldn't figure out a way to weld the back of the new roof skin to the cab, so decided to use 3M panel adhesive. The roof skin came from Auto Metal Direct and I've got to say it was a pretty good fit. The upper doorframe structure came from GMCPaul's (site vendor).
After cleaning all the bonding edges to clean metal and wiping with Eastwood prep I did the bead on both surfaces, spread it then another bead on the roof panel. I thought I had only 30 minutes work time and was by myself so didn't get many pictures. I got some of those windshield installation suction cup thingies and stuck them on the top of the roof skin, then flipped it over for this. Once I had the glue on just reached under, grabbed the handles, flipped it over and dropped it into place. I agonized a couple hours over a few beers figuring out how I was going to do that without messing up the glue!
All clamped up and used straps to hold the rear tight. I thought I had more of the spreader clamps than what I could find. I thought they were all in the same place so didn't look for them before spreading the glue. So a bunch of little c-clamps to the rescue. Only managed to glue one of them to the roof
Paint sticks under the straps kept the straps from being glued on, but as expected I'll have to sand the remains of the wood off.
Overall, I see a pretty even squeeze out all around so pretty sure it is sealed. I'll still do seam sealer to be sure, and for the look. Where the back of the panel meets the top of the cab rear did not come out totally even. I'm not sure if extra filler is in order or not. I'm inclined to think nobody will notice with white paint. Anyway, the roof is done other than some cleanup, filler work on the inner door frame and the seam sealer so mostly past this hurdle - yay!