Drew,
If your data plate has the code A62, then it was a factory rallye dash. The door panels were unique to Gran Coupe's with the "Gran Coupe" emblem, and the faux wood grain insert in the reveal portion of the panel; that is standard GC interior stuff. GC seat patterns were alltogether different, and were year specific for Gran Coupes. Your headliner material is also different and unique for GC models, and is quite similar to modern headliner material.
You have a great car to start with; it is going to look fabulous when it is complete! Do you have a pic of the data plate? A lot of us are just curious to see what options your ride was born with!