Rick,
All the sunroofs were metal panel . . . some were covered in vinyl if car had vinyl roof. I believe the panel is same size of a, b or e body . . . or maybe the a was smaller ??? If you did have a seal for the rear and the front of the b or e body panel, it could be trimmed for use on the a body.
I have a 74 Duster360 with factory sunroof. At some point I should be replacing my seals as well . . . would be nice to have a source . . .
Of course, one could always try American Sunroof Company in San Diego . . .they were the ones that built the sunroof unit for our cars. Not sure if they would have any suggestions . . . .
Cheers
Mark