Is anybody making parts?
My son and I completely restored a '74 Dart Sport - every last square inch of it - and we were able to find almost everything we needed either in local auto parts stores, internet web sites, or just by simply posting "PARTS WANTED" ads here and on other MOPAR-related forums.
We are almost done with his '74 Gold Duster, and the same story is true. Granted, it takes a bit if patience, we spent about 3 years on the Dart Sport and about 1.5 years on the Duster.
Post a list of what you need in the "PARTS WANTED" forum and you might be surprised what you find. As a matter of fact, I have a '73 Duster parts car with some good stuff still left on it.
Good luck on the search,
Jerry