Go for another test drive with the vacuum advance disconnected and plugged. If you don't have pinging, you need to get an adjustable vacuum advance canister and dial that in properly to eliminate the pinging when it is reconnected.

If it pings at mid rpm and not high, slow down the mechanical advance curve. If it pings at higher rpm but not mid, restrict the amount of mechanical advance. If it pings at low rpm, reduce the initial timing.

Your dyno guy should know how to dial in the right advance curve.