It's interesting reading about the placement of the fan temperature switch/s. Unfortunately my just purchased L is a mess cooling system wise. Fans run all the time, why, well turns out there is no place for fan switches in the rad!! Bleeder from the rad goes to the rear of the car but is not hooked up to the swirl tank!! Non Cleveland thermostat is fitted. Thankfully I had only driven it 12 miles before I found these issues.
I'm keeping things simple and have used this fan switching system successfully previously. Whether with or without an electric fan just about ALL engines primary temperature control is via a thermostat placed at the outlet of the engine block. This is "real" engine temp. So for the fan switch, it follows that the ideal position is similar. eg. Thermostat housing or radiator inlet. On my Pantera it will be placed in the vacant 3 port vacuum switch position in the water pump, that "Ford" often uses to monitor engine temperature. Remember Ford uses that position to switch vacuum to the distributor vac advance to speed up the engine to increase fan speed on various front engined cars with belt driven fans if the engine starts to overheat. So it works for temp sensing!
I have two other front engined Fords where I switch the electric fans (originally belt driven) from a switch mounted in the thermostat housing treaded port. Our cars do not have that facility, hence the vacuum switch position. (I believe this position still measures similar temp values to the outlet of the thermostat). Quite simply, it works on my other 2 cars. I will probably use a 92 deg C / 87 deg C switch. Thermostat will be a 77 deg C cleveland type, bleed hose will be fitted to the inlet pipe of the water pump. Standard type overflow tank is fitted. Oh and if the fans don't control the temp early enough or or to late, I'll change the fan sensor switch to a different value. I'm 95% confident this will work, as it has in my other cars. The only issue may be the standard fans. The rad is brass and looks real good, but I'll be also adding a water strainer/filter. I will definitely let you know what the result is. (good or bad)
I have never understood why you would want to measure the returning coolant temp to control fan switching/engine temperature. It's simply well and truly after the fact, so to speak!!