I didn't realize the Wild West forum had become so inactive. I just noticed many of these posts are "dated" long ago. I do hope answers to these older questions were found over at FordFE.com or other good FE forums.
I want to elaborate on my odd statement, "and a few 1966-later heads have neither" in my previous post. By "neither", I refer to the few FE cylinder heads cast from 1966 (C6AE-R, etc.) which have low-ceiling and high-floor exhaust ports, making them "centered" ports which are a bit smaller than the high-exit and low-exit ports. Never fear, as the smaller "center ports" have real performance potential, as the "low ceiling" is present only at the port face, not inside the runner, and the material is readily "ground-out" of the head to produce a nice-flowing high-exit exhaust port that performs very well.