I haven’t made it to harbor freight yet for the infrared temp tester, but I think I ruled the gauge out. I had a stack of clusters that I needed to test anyway so I ran it up to temp and started swapping out clusters. 3 separate temp gauges showed it was running hot.

At this point I believe that head gaskets are impeding flow and/or I have sediment in the block. It is flowing coolant but not enough. I’ve been through the whole system unless someone has another idea. If I’m going to do head gaskets I may as well pull the engine, remove the freeze plugs, clean out the block, and install in one of my 68 Chargers.