The 66 Signet is home, well at the shop for now...

Looks cool!
When I was younger we had a '66 Signet so Im partial to the look as it came out of the dealer.
It looks really good so I would leave the exterior alone.
I would like front disc brakes which means at least 14" wheels ( looks like it might already have them on) and while you're at it consider putting the large jolt pattern on just because the wheel selection is better. I would put 14" steel wheels with '66 spinner wheel covers ( the last year of fake knock off prongs ).
Then I'd plan on AC sometime ( before we know it it'll be spring ).
Then drive it.