RI/CT machine shop recommations

I have limited experience with this type of failure, but ,I could guess.
Detonation induced preignition.
My guess is detonation broke the rings,and
the broken rings led to preignition,
and that spelled the end.
The clues are the lack of scuffing on the skirts, and the fact that you did not mention any holes in the piston crowns.
You will have to find the source of the detonation, which is usually too much heat in the combustion chamber, but I don't see the evidence on the skirts. So I guess it would then be just a case of too much timing,or too much compression, for the fuel octane rating.
So because of the extent of the damage,you will have to check everything; which is higher octane fuel, the compression ratio, the entire cooling system,and the entire ignition system,and if you can't find it there;the exhaust system.

Engine Basics: Detonation and Pre-Ignition by Allen W. Cline