Here’s info I gathered when I investigated the tag on my carb.
Carb King supplied the details.

On 10/10/11 I carefully removed the tag from the carburetor. Can you see the "R" and a "P" just beneath it at the top of the triangular tag? The "RP" stands for Rochester Products.
Kudos to Stovebolt.com forum member "Carbking" who correctly decoded the tag.

70 = prefix used for all
mid-to-late 60's Rochester carburetors
2 = 1960's
3 = 1963 (the 1st year carb was introduced)
0 = 1 barrel carb
1 = Chevrolet
7 = manual transmission
C = 3rd production engineering change
F5 = June 1965
90 = badge # of the final inspector
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