Help needed on Identifing Numbers on a Carbureator

This is my first post in the group, but have been reading the newsgroup
letters ever since buying my 1972 Corvette nearly two years ago. I have
used the advise of many of the writers and purchased many of the
publications that have been discussed. This leads to my point of writing. I
have a chance to purchase an original 1972 (#matching, confirmed by Corvette
Black Book) Carburetor. My dilemma is there is another series of numbers
that I can not deduce. They are located on the carburetor and read
7042203(Black Book Confirmed) OC and below 2731, 909 on the large
butterflies. Any help would be greatly appreciated.

Thanks in advance
Steve Eftink
Proud Owner of a 1972 Bryar Blue, 350, 4 speed Corvette