I only use the temperature probe at the thermostat housing. So that is actually the temperature changing.
It would be interesting to run another thermometer to the head but where would I mount it? The GMC heads have a threaded fitting on the top surface of the head between cylinders 5 and 6 that can be used for a mechanical (bulb type) or electrical gauges and another threaded fitting in the thermostat housing which are only used from the factory for electric gauges. When I bought my truck it had a set of electric replacement gauges with the temp sensor in the head. I moved that electric sensor to the thermostat housing and installed the mechanical gauge in the head. I don't know if you have both these mounting points available in a Chevy head.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
| 
