I drilled 6 1/8" holes in the thermostat, now it runs at up to 220 degrees but doesn't go wild like before, but it cannot absolutely be running at 220 degrees, I think, because it'd be pinging, boiling, etc. I have not filled the block THEN put in the thermostat, I'll try that but I'm thinking this is a RPM AIR GAP for VORTEC heads, 385 fast burn, the water passage into the head narrows a lot drivers side of the thermostat and the temp gauge goes right in the middle of that water flow. I used an infra red thermometer on it today and the temps all around are 135 - 145, etc., except the housing the gauge sending unit is in, it was the hottest, about 165 - 175, of everything.
Maybe I need to move the sending unit?
I'll keep the post current.