If you are wanting to retain a two barrel:

There is NO better two barrel carb for your engine!

if you wish to change (not necessarily an upgrade for a stock 265 engine) to a four barrel:

(1) a stock Chevrolet 283 four barrel intake with the Rochester 4-Jet that would be original for a 283

OR

(2) same manifold as above with a Carter 9400s or 9410s (requires a 1/4 inch fiber spacer)

OR

(3) aftermarket four barrel intake with either the Carter 9400s or 9410s

OR

(4) same as (1) but Carter WCFB for 283 (EXPENSIVE because of all the Corvette restorers)

Sorry, but NO recommendation for a NEW carb for your engine.

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