What are these Pistons and what's up with my block

Hard to tell if that is a sleeve from the picture, but sleeves are OK. At
040 over, roughly 8 cu in. Pistons are aluminum in color, that gold is from combustion, not sure from the picture if it's an intake, where the clean area is, but intake I think. Fuel is cleaning the area.
Someone else can zero you in on gasket thickness. That piston is pretty much a stock replacement.