Getting a 8 cylinder “balanced” reading for a single MAP sensor is hard to begin with, and would seem especially hard for the old style Long Ram design.

A EFI that has software that has individual “tweaks” for each of the 8 cylinders might overcome many limitations if it allowed adjusting BOTH fuel injector flow and ignition timing.

600 rpm, 1600 rpm and 4000 rpm behavior at each cylinder might be WAY DIFFERENT with the old Long Rams.
Modern state of the art intake V8 manifolds vary 8% per cylinder according to the Bosch Automotive Hankbook.