The only difference between the two that I'm aware of is that the 72 has EGR and ported-spark vacuum connections. Later models had electric chokes, but I'm not sure when they were introduced on production Mopars. Venturi size on early and late models is the same. There's no reason why a 72 carb would not work on a 71 manifold as long as the un-used emission ports were properly capped.
