Need help

My son just purchased a 1968 Dodge Dart 270 .it has a 318 2 bbl engine..our problem is that the car needs new brakes ..replaced front rotors and brake pads..need to replace rear drums but having problems locating them ..every parts house show a 9 " rear where as the ones we pulled off are 10"..went to classic industries and spent over an hour looking for replacement but to walk out empty handed..anyone out there run into this same problem??