As mentioned, you will probably go to a lot of vendors. I bought from several.
GBodyParts.com Online was great. He has a ton of stuff for interior and exterior.
Also,
Kirban Performance - Buick Grand National Parts, T-Type, Turbo T, GNX Parts, Chevrolet Chevy Corvette Parts, Ford Mustang Parts, Pontiac GTO Parts www.kirbanperformance.com is another good vendor.
N O S 4 G N . c o m (remove the spaces) has a metric sh!t ton of new old stock parts such as gaskets, trim pieces and a long list of other stuff. Glen is great to deal with as well.
For some custom touches, hit up
Welcome to GNSPerformance.com. Scot is a kick ass vendor, too.
If you need headlight bezels or a grille, go to
www.WorldOfMotorworks.com and check out their reproductions. Great pieces & Paul is another awesome vendor. He also carries other items you may need
The list goes on and on. Basically, see what all you need then just start surfing the vendor's sites. Also, be sure to check the classifieds section on the board. I bought several things from various members here and had great success.
I see you mentioned glass specifically. Windshields, door glasses & back glasses seem fairly easy to locate from my personal experience. Quarter glasses on the other hand... Not so much. But, if you have access to a glass shop of a decent size with good distributors, you should be able to find them. As far as I know, the only NOS stuff still out there will be the glasses with the chrome trim. But this can easily be painted. Be sure to specify no vinyl roof.
Good luck & have fun with your resto!