First welcome to the site. Hope you find the information and help here useful in your concours related projects.
Did see you asked the same question over on the Boss 302 site
Looks to be that its a product for touching up engine compartments. Guess it might be very similar or the same as the paint used for the pinch weld black out looking at Ford documentation.
The extension appears to indicate the size and or container - G = gallon, - C = 3 oz and so on.
Found
EP 1724-G - listed as the engine reconditioning paint in Ford black. 1 gallon container
EP 1724-C - listed as the engine reconditioning paint in Ford black. 1 quart container
AE60 1724-A - exterior black acrylic enamel paint (glossy) 3 oz container
AR60 1724-A - a 72 exterior black repair paint (code 1C) 3 oz. -C = qt container -S = 6 oz spray
AR60 1724-C as a 65-71 exterior black repair paint (code ) in quart size
AE60 1724 (blank) - Low gloss black for 68 & 69 tutone hood - cowl - rear deck area. (code 5) 3 oz. -GS = 6 oz spray container
Could not find a listing for repair paint for the 70-73 low gloss paint in the 1975 reference as I would expect