I assume you don't have a dial back timing light or marks on the harmonic.
Unhook and plug vacuum advance again.
Set it to about 5 before TDC and go for a drive forget the vacuum advance for now if it pings back it off till it stops if it don't maybe try 2 more degrees. if it's still fine go home set the in gear idle the way you want it helper in the car is a must.

"Now" plug the vacuum advance into the timed port (the one to the left) should make no change in idle drive around and see if it pings at cruise under light acceleration.
If it does tune vacuum advance back with 3/32 allen key in through the port on the vacuum canaster on the dizzy turning counter clockwise a turn or two at a time till any ping under light cruise load is gone and you should be good to go.