I now have doors with weatherstrip in place, windows that go up and down, and (I think) have located the roof rail seals. Also a pair of long trim pieces that conform to the roof shape - is this the channel you refer to?

The body has several small openings along the rail that look like they should accept either a screw or some type of clip (there's a round hole with an elongated small slot). Without an assembled car to study, it's a bit difficult to know what kind of fasteners I need.

I do have a 1970 Plymouth FSM left over from my first (and second) cars, both '70 Valiants, but not sure that's going to be useful for a '72?