From my experience the small port single planes make more torque. That be why they made them, the 273 had them, and marine engines run them. The highest HP and TQ 318's ran them too, in a 2bbl version.
I'm interested in the difference, but I don't have a performer and I do have Streetmaster, on the car. As the difference in performance seems to be in the eye of the beholder I'm keepin' it for now... (I still can't help but wonder hahaha)
good info thanks.
BTW Doktor X or anyone for that matter, check this out: