65 Valiant Wagon Parts Needed...

The Australian version of the round reverse/reflector lens you need is available new. In Australia, the regulations didn't allow the rear turn signals to flash red, they had to flash amber, so the round amber lens did double duty as rear turn signal and the back-up light. Safer than the American red brake/turn/tail setup; latest (American!) research shows a car with amber rear turns is up to 28% less likely to be hit from behind than the same car with red rear turns. See this post for how to set up the wiring for red brake/tail + amber turn/backup like the Aussie cars. That said, if you don't want to do that, contact the vendor anyhow; he's sold me "nonstandard"-color lenses off stock tooling before so it's likely he could probably supply a clear/white version. He's also got the left and right brake/tail lenses for your wagon.

The door lock knobs are easily and cheaply available at any auto parts store that carries the "HELP" line of repair parts. They're chrome and come with the round bezel/grommet. The original lock knobs were made out of black plastic and painted to match the interior, or made of colored plastic; you can get black plastic ones on eBay, but the chrome ones look fine with any interior color.

The interior door panel interchange is '63-'64 Dart and Valiant 4-door sedan and wagon. Can be tough to find really nice used ones, but sometimes you get lucky. New ones can be had out of Australia in either the '63-'65 or the '66 styles, in whatever color you need.

Wagon-specific parts (seat latch, etc.) are going to be a "go fish" situation. '63-'66 Dart/Valiant wagon only.

See here for a listing and description of reliable parts sources for the early A-bodies.