Assuming you have a dial back timing light - Disconnect and plug the vac advance. Hook up the timing light and rev the engine until the timing stops advancing. With the revs up high and not advancing further, set the timing at 36 degrees and lock it down.
If you do not have a dial back timing light, you need a magic marker line at 36 degrees. Same procedure otherwise.
Hook the vac advance line back up and you are done.
You should consider running manifold vacuum to the advance can. Not stock that way but it will run better/cooler. Be sure to use the vacuum advance can that will fully deploy at 9" of idle vacuum. Ask if you need more detail here.
If you still need more ignition advance at idle, you will need to remove mechanical advance from the distributor mechanical advance mechanism by reducing the slot length.
The weights and springs are modified to alter the RATE of advance. You want the mechanical advance to be all in by about 2500-3000 RPM. As fast as your gas quality will allow.