2bbl stuff will not work on a 4bbl carb without cutting and welding, you will need the 4bbl brackets and rod. This applies to the throttle cable bracket, the return spring bracket and the kickdown rod. On the 3 piece kickdown linkage that a-bodies need the rest is the same between 2bbl and 4bbl, everything from the bellcrank on the throttle cable bracket to the transmission lever is interchangeable.
Just so you are aware and don't buy the wrong stuff.