The big question is if the rest of the engine set-up can take advantage. Some engines simply cannot draw enough volume of air through a bigger carb to take advantage of the larger air intake, and the engine will bog down, and drive worse. A '72 small block V8 should be able to handle a small 4bbl (like a 550 cfm), but, unless you replace the intake manifold with a 4-bbl manifold, a 2bbl-to-4bbl adapter will kill most of the advantage of adding a 4bbl. Plus, the factory-style single exhaust is pretty restrictive. If air cannot get out efficiently, It cannot get in efficiently.
For that engine, if I were to change to a 4bbl, I'd also change the intake manifold to a better flowing Edlebrock, put in a better breathing camshaft, like a Crane street cam, better flowing headers, and the take it to a muffler shop for dual exhaust. Otherwise, your not getting the best bang for the buck.