Unless you happen to have the triangular sheet metal tag that the carb came with originally, held on by one of the top cover screws- - - - -the one that usually got lost during the first rebuild, identifying a Rochester is a crapshoot. Several main body and throttle body casting numbers were used across a wide variety of very differently calibrated carbs. Carb King has posted a pretty comprehensive list of the various tag numbers, but without the tag number, it's a guessing game.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!