Once the throttle opens past idle, there is NO difference between ported and manifold vacuum
Ported Vacuum Advance was a crappy early-emissions-era crutch, and if you don't have an emissions-driven Ignition Advance Curve in your dizzy, or an EGR, A.I.R. Pump, catalytic converter, etc, why bother with it?
Checking and recurving the centrifugal advance curve is easy, weights and springs to do this are readily available, it's easy to do with just a timing light, pliers and a screwdriver. Search here for the desired timing advance specs. Or you can send it off to WSA and he'll do a very good job of it for you.
Once you have a known, non-emissions (i.e., efficiency / performance), use manifold vacuum (like gawd intended) and forget about it.