Too much cam?
A 1300 rpm idle would eliminate some of your vacuum advance timing curve. Are you sure you have the vacuum advance hooked to a timed port on the Holley? There are 3 ports for that on the Holley you have,so it's an easy mistake to make. The port you want will NOT have any vacuum at idle. Could also be a hole in the vacuum advance diaphragm or a leaky vacuum hose/connection. Also check your mechanical advance mechanism/curve. Make sure it's free to move/not seized. What springs are in there?