The style in the A-100s are the early cone style that are not able to be re-keyed. So you have a few choices:
Buy NOS sets that have 4 door locks and an ignition cylinder
Find a used set or 2 and have 1 or 2 keys
Swap to later flat style locks that can be re-keyed. This may require some mods. As you can see, the early shown have a stud, the late have a hole. I know that the arm on the back pops off easily if you aren't careful! You can also see the removable cover on the later one that allows the pins to be changed (re-keyed).
Here are pics I found with a quick search, and the sites that have them. NO inference made as to the sellers or prices.
EARLY STYLE

http://vintagemoparts.com/category.php?id_category=31
LATE STYLE

http://www.carlocksandkeys.com/servlet/the-889/Dodge-Charger-Automobile-Car/Detail