I'm not sure about the throttle plate size, but the 2 barrel used on the 265 and 283 engines had smaller throttle bores and venturis than the ones used on the 305, 327, and 350 engines. They give better throttle response and fuel economy than the bigger bore carbs, especially if they're used on a small displacement engine like a 250 or a 261, etc. For instance ;

https://www.ebay.com/itm/314662605420?

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!