One thing I would like to add to this, when I had a 70 440+6 Cuda it had an aluminum on it when I purchased but came with the car's original cast iron.
Wanting to put it back to as original as possible I re-installed the cast iron intake and it had a noticeable seat of the pants difference in performance.
Maybe the cast iron was a bit more restrictive???? But my hiney felt it!
Ron