To find out if the leak is around the carb itself spray some carb cleaner around the base. If the residue sucks in that's where the leak is,then install new gaskets.Also check the vacuum hoses running off the carb,personally I would change them all. Good Luck
Get a can of Carb cleaner while the car is running spray very lightly arround the base of the carburator, manifold and if the engine sputters or chances rpm's you found the problem. Now if is a hose use a soapy solution with a rag and spread a bit at a time thru the hoses and see if any bubbles appears.
Don't know what engine you have.
But one common mistake made when working on the Windsor family of engines (221, 260, 289, 302) is failure to match the machining of the intake manifold to that done on the heads.
If either has been machined, the other must be machined to match it. Otherwise oil and vacuum leaks can occur.