The original carb for a 1961 305 would have been a Stromberg, which (opinion, others will differ) is 10 times the carburetor compared to the Holley. They are also significantly more expensive, which is why they sometimes get changed by those looking at the immediate bottom line rather than the long term.

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