Congrats on the find and its condition! Looks like it's coming along great and deciding to bring it back to original color is a good idea, IMO.
Not all plants used a dash character when special paint was ordered, 1971 Arlington happen to be one that just the area blank. Some used a dash character and some even used the DuPont mixing formula such as 926-98371 on the tag. Where a vinyl top (or convertible top color) was appropriate, the letter for that color would be used in lieu of being completely blank, such as your C only, or on plants that used the dash character it'd read - C.
The "Carolina Blue" wasn't unique to 71 & 72 as I've seen it on 69 & 70 Chevelles as well.
