[olddog]

When the intake valve closes ABDC is what impacts dynamic compression. Advancing or retarding the cam will impact this, as well as the duration. Looks like the old cam had 10 deg more intake duration. The new cam (less duration) would have increased dynamic compression, but I haven't a clue as to how much.

The AFR and exactly where the timing is when it pings would be helpful to know. There are some guys who know a whole lot more than me on this site, but you are going to have to give them a lot of specifications and information before they can help you. I think I have pointed you in the correct directions to look. Good Luck.