I have had good luck with the rebuilt Rochester carbs from AutoZone (I do not see one listed, now). As suggested above, do not give them your old carb as a core until you have run the new carb. If the new carb leaks where the top "cover" meets the base, or if it leaks where the throttle plate pivot exits the sides of the body, take it back and get another one.
Years ago, I purchased two rebuilt 1960 261 carbs from Jim Carter. They both did not match (one had the different air cleaner attachment that was used in earlier years). After quickly being sent a new carb, the carbs ran fine and have been in service for over 10 years.
Rockauto.com has one for about $90 plus shipping, but it is most likely rebuilt (it has a core charge).
