[Formulajones]

Pinging at light throttle is most likely caused by the vacuum advance. Especially since your initial and total numbers are very conservative.
You didn't mention how much timing the vacuum advance is bringing in but on a combo like yours I wouldn't want to see more than 10-12 or so and wouldn't think anymore than that is needed.

You'll probably have to dive into the vacuum advance and modify the slot to limit it's travel.