Well, I tried it. I moved it from ported over to full vacuum. interesting results, at least to me, admittedly still not understanding it fully. It races and I hear some sputter out of the exhaust while it is on the idle cam. Once it comes off the idle cam it is incredibly smooth and if I closed my eyes I could swear it was a prius running. But once I hit the gas you hear the normal 289 exhaust note. Drove it around for a while and cannot tell in difference in power or sound once off idle. But you stop at a light and I can barely hear it.
When it is idling in the garage I still hear a sputter in the exhaust every 3 or 4 seconds. It may be due to having the initial timing set pretty high? Need to play with it some more, but definitely interesting.
1966 Coupe / 289 4bl