Piston pin bad ?

Detonation damage is usually around the circumference,, and usually worst on the side opposite the spark plug..

That looks like its been shot peened..

My eyes must be getting old,, I didn't see any piston pieces missing..

Is there a better pic of the piston missing a piece.. thnx?

How far did you advance the cam,, ?? That could certainly aggravate detonation.