Ok, finally sorted Megalog Viewer to show the temperatures I recorded on a 20 minute run. The car was already hot.
The ambient temp was about 20C and this is shown as the blue line Temp6 from a sensor behind the grille. It does get slightly warmer after idling. See the bottom white line for RPM.
Yellow line Temp7 was recordered at the heater air intake on the firewall under the bonnet and Red line Temp4 was stuck up into the heater intake air box through the water drain hole.
The air heater air box (Red & Yellow lines) heats up but cools quickly as the car moves off.
The Green line Temp5 was from the firewall/ brake master cylinder area. The top White line is the MAT which is located at the very end (cyl 6) of the plenum tube. The air intake is right behind the grill and only takes air from the front. Interestingly, the MAT closely follows the Temp5 graph in temp and gradient. The sensors are about 200mm apart but the MAT is inside the plenum.
The Red CLT line is the water temp coming out of the engine (original temp sensor position) and the Green Clnt2 line is the water temp going back into the water pump housing. This is my modified cooling system using a remote thermostat and a bypass hose to try and mix the cold radiator water with the hot engine water before they go back into the engine. However I am still getting a swing of about 12 degrees coming out of the engine. The goal is to have the engine water temp as stable as possible.