Time for the '81 Bertone rear glass to be removed and the sorry replacement work cleaned up. Some 20 plus years ago the rear lite was replaced for some undocumented reason and that work left black butyl all over the interior trim around the glass. In addition there was surface rust on the sheet metal at the bottom of the glass and an unknown question about any pinch channel rust.
No rust found in the channel front or back except for that pictured.
I have been reading all I can find about how to install the glass and trim on what is apparently an unique-to-Bertone set up. The bright trim has/had a plastic trim piece that did not survive removal and nothing remotely like it has been found in hours of searching on the internet.
Ideally, I would like to put it back as original but that doesn't seem likely.
The issue and question before the forum at this point is how to reinstall the glass and trim. Originally butyl adhesive was used in the pinch channel to hold the glass and then a round butyl tape inserted into the slot behind the bright trim which secured the trim to the glass and provided a black trim edge in the trim to paint gap. Best I can tell a 5/16" round butyl tape was used.
Now, after much research it appears that some professionals use urethane to fill any gap between the glass and channel which provides a better level of water/debris intrusion protection. Elroy, the glass doctor of 20 years ago used clear silicone caulk for that purpose. It, of course, did not adhere properly and pretty much just pealed off with trim removal.
I know I have to clean the pinch channel clean enough for repair and paint which is a big job. Then install the glass. Then fill the channel gap with urethane flattened with a stiff piece of nylon paddle. Then use the 5/16" round butyl to secure the trim to the glass. I thought at this point that I would tape the paint/butyl line to get as clean a line as possible.