[Big-Foot]

Smash - sorry to see that... Looks like the broken ring was the compression (top) ring. The skirts being blown right off that slug tell me that unless you had some sort of power adder (N2o), Supercharger or experienced severe detonation which would normally just blow the headgaskets, the cylinders had been bored/honed well beyond the max tolerance of the pistons. Forged pistons can be clearnaced a little on the loose side.
Cast pistons (hypereutectic or not) must maintain a very close tolerance or this may happen..