Jerry - I think if you look again, you will find your 401 has a 4-bolt 2-barrel Stromberg type WWC. The WWC was about the same internal size as GM used on the 2-barrel passenger engines (Pontiac 389 is a good example). Chrysler used the WWC on their 383 passenger engines.

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