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

Yup, most likely not sleeved. The clean spot is where the fire ring of the head Gasket was. It's metal, so it won't leave as much crud behind.

The yellow/gold is likely from gas pissing down the intake. Either percolating after shutdown, or other carb/tuning issues. Either way it's where the gas has washed the carbon off the top of the piston.

The pistons are sitting down in the bore like a normal 318. "even with the deck" would be just that. The 4 reliefs are normal.

Your compression isn't likely to be much over 9, if that, no matter how thin your Gasket is because of how low the 318 pistons sit. You'll have to measure actual bore, how far down the pistons are, and cc the heads to get an accurate figure.