The last three days have been very hot and have tested the cooling system....
Monday was hottest at 42 deg, sitting on 100 K's the engine coolant temp stayed at 90 degrees with the A/C on and fan on three. Thermo fan ran continuously.
Tuesday was 40 deg, as above, 100 K's and A/C on, engine coolant sat at 88 degrees with thermo fan running continuously.
Today was 38 deg and the coolant temps fluctuated between 86 to 90 degrees as the thermo fan stopped and started.
Previous days around 31- 35 degrees I switched the thermo fan to start and stop with the A/C compressor, engine coolant did not go above 86 degrees.
When hotter I don't have the thermo fan switched to run with the A/C as when the thermo fan starts it powers the A/C compressor which would run continuous (as the fan does) and probably burst lines or freeze condensor or something
Anyway pretty happy with how it is all working now, no more overheating problems
So to update, I have the radiator from a rattler ( 27mm thick cores compared to the stock V6 12mm cores )
Also running a Ford FG 20 inch electric thermo fan mounted in the stock radiator shroud.
Engine fan is deleted.
Fan is controlled by a cheap digital box thing with a sensor mounted on the outside of the aluminium water transfer tube that carries the hottest water to the thermostat.
So far very reliable, once I sorted out the wiring for the thermo fan
70 Amp gear is the go