In all the discussion about adding a PVC system to a Y-block, there has been lots of discussion about "porting" the air cleaner, carberator, and oil fill cap. I assume a vacum port is nothing more than a tube fitting which allows passage of air, gas, fumes or combination of, from one location to another. The diameter of the "vacum port" would be consistent with the diameter of the tube used to exit the PVC to whatever locations were being "ported" to close the system? Am I thinking in the right direction?

Darrell Howard Whitefish, MT Outlaw 56 Ford F-100's

That is correct.The diameter of hose and fittings will be the size that will fit the outlet on oil cap if you close the system and the size of hose that will push onto the PCV valve outlet.