Very few four-barrel carburetors have ever been made which could surpass the original Q-jet in fuel-efficiency on a basically stock street engine (and none made by either Holley or the e-clone).

Rebuild the Q-Jet.

You need no adapters, the air cleaner fits, etc., etc.

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