I believe you had the head pressure tested but did you check the flow? This head has been on both blocks. Is it possible something is blocking the water jackets in the head?
You should see water flowing at some point in the warming process. Start it with the cap off and see at what point hot stuff come out of the radiator.
Does water flow through the radiator? Put the cap on disconnect both hoses and see if it runs out the bottom hose as fast as you can put it in the top.
With both hoses disconnected from the radiator and the thermostat removed put water in the top hose and see if it comes out the botton as fast as you are putting it in the top.
Get new radiator cap. Hang it in the garage. Drive a new car under it.
