Found this in my shed yesterday....

Is there a model # stamped on one of the mounting feet?
Couple of comments:
- if this is a Comp Series carb, it is the 2nd iteration
- The original Comp Series were 500 -750 cfm, #s 4758 - 4762
- Early 60s Buick engines had AFBs with the 5" airhorn, known as the 'E' series.