Have you done a cranking compression test?

If the cam has fairly short seat timing, the cranking compression might be fairly high, and/or the dynamic compression might be close to the trouble zone.

There are other items that can contribute to the pinging....... stall(if an auto), rear gearing, engine operating temp, etc.

If the cranking/dynamic compression numbers are high enough where it’s a concern, I’d probably look at slowing the mechanical advance curve down, and employ a small amount of vacuum advance to get the timing up where it should be during part throttle cruise.