Vacuum advance issue

If its pinging in neutral something is way wrong. It will ping when there is too much advance and load is added. For example accelerating gently up a hill at 50 mph can be enough to result in ping. This is annoying but will not cause major damage. Ping under full throttle or nearly full throttle can rapidly lead to damage. Back off the throttle. This is too much mechanical timing for the conditions (rpm & load).

First step is to map out the mechanical timing. By that I mean is measure timing and rpm from as slow as it wil lrun through the rpm you are willing to take it. Write down both and rpm as you go along. Then you can compare that to a factory 360 or mopar performance generic timing. If its in the ball park, then drive it and see how it does. If it pings or has other timing related issues, they must be addressed before using vacuum advance.

Second step is to map out the vacuum advance.
Then with both the mechanical advance and the vacuum advance you have information needed to decide what to do.