Agree that it would be best for the OP, Challenger, to measure timing from idle to as high as he feels comfortable.

My comments about the vacuum advance were about effect of not slowing the rate mechanical advance before 2000 rpm.
Its not hard to reclock distributor to change where the vacuum canister points on a small block. No disagreement that is something to consider.
No idea what engine Challenger is working with.

When vacuum advance is used with a mechanical timing curve like shown below, the engine will ping under light to moderate throttle in the 2000 - 3000 rpm range.
Been there done that.