Headers vs 340 manifolds

headers on a stock 340 through mufflers aren't going to gain anything noticeable.
3/4 cam was a cam ground specifically for the rpm operating range on 3/4 mile stock car track which would have
no low rpm requirement....or maybe a cam with 12 lobes?
while i won't address the stance on headers, can you shed any light on how you came to that conclusion on the 3/4 cam?