Brian reminded me that he put in a 160 degree thermostat, but used GM specific coolant. We'll do a flush and fill with water and Water Wetter ... and clean the radiator. It was easy to put in a new Miata radiator ... I'll check our shop manual on removing the Z06 radiator for a thorough cleaning.
Any opinions on using regular tap water vs distilled water vs filtered water from my Brita water filter system?
Use distilled. The water in L.A. is very hard and will deposit lime in your cooling system (not conducive to flow or heat transfer). A Brita fiber & carbon filter won't remove the minerals from the water. If you have a reverse-osmosis filter then you could use that water.