65 Barracuda 318 Rebuild, Cam, timing, lifters maybe a kit?

I have a question. I am still learning about cam selection myself. Why would a split pattern work better with factory manifolds?
the skinny is this: Using factory manifolds challenges the motor (think of an air pump) to exhale, or get rid of the exhaust. Split pattern cams allow more lift/duration on the exhaust side of the cam to help exhale. Less intake, more exhaust.