So what's the deal? Which carb is the right one?

A little more info on the Holley 1945 from 1974.
Two 1945 carbs were used on 225 engines in 1974 without Calif. emission pkg. and with auto transmission.
3751424 - Holley R-6724A and 3830402 - Holley R-6938A.
Chrysler superseded the 3751424 to the 3830402 in mid 1974 model year.