Is 2 core radiator enough

We are running a 67 318 in out 74 dart sport. The 318 has a 4 bbl carb, RV cam, headers, and I zero decked. We are using a 70/30 radiator fluid/ water mix in a two core radiator. The engine seems to be getting really hot when we feel the radiator hose. Is a two core radiator enough cooling or does a 318 need a three or four? Thanks