In days gone by..............

There were a lot of 4 barrel carbs that flowed less than 400. The smallest of which I am aware would be the Carter WCFB used by Studebaker on their 259 CID. It flowed about 295 CFM.

Do Studebaker 4 barrel carbs grow on trees? Nope, kind of scarce, and not overly cheap.

Can the 228 use 295 CFM? Don't know. With a big cam, and good exhaust maybe.

Jon

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop