We sorta covered that a little. He'll eclipse the power limit for the factory block pretty quickly running a head capable of big flow. Remember, Cadillac built 500 kyoob motors that were torque monsters. Ford even bigger at 534. They all used iron heads. Building for low RPM torque doesn't require an extreme high flowing head. It just requires what I would call matched flow to the intended use and that's within the iron head's grasp.
