Hypereutectic pistons and failures related..

You said it yourself... Hypers dont absorb heat as well so the oil won't appear black on the skirts or ring lands. Sometimes it will leave some black soot in the machined grooves above the top ring. But mostly the dome, skirts, and ring lands will simply be wet with oil. I had a 383 I had to re-ring after the owner washed the rings of the new engine out. It wasnt sealing well but not smoking. The piston tops looked like yours. See if one of the shops does a lot of circle track stuff. Someone that can get you a report with a profilometer. Maybe ask the shop you're using what stones they use to hone. What do they finish with?