I hope you didn't drill anything Roman, as you didn't have to tap the waterpump to put C Ludwig's sensor in.
it would have fit,like stock.(stock threads,screws right in)

 

I'm wondering, the new rad I bought puts the rad outlet 1.5" too low. What are the downsides to putting the thermoswitch in the return hose from the rad to the engine? The adapter for the sensor would extend the hose enough that I wouldn't need to buy a new hose. It would also put the sensor wiring right by the wires for the fan motor; keep that part of the harness simpler.

 

I don't see much difference between the upper and lower hose for your trigger but you'd need a different switch, based on location.
A switch in the lower hose would see much lower temps than one in the upper, you'd need to know how rad exit temp correlated to the coolant temp measured in the block (what your gauge reads).

 

Bah, there's never a simple solution, is there? XP Ah well, I have to replace 4 fewer wires in the harness than I previously thought, I'll buy a new hose.

 

Putting the trigger in the upper hose is the "simple" solution...what you wanted was a "convenient" fix.
Not quite the same.

Are you planning on a failsafe manual override in case the trigger fails?
It's pretty simple, you can use the stock harness for most of the wiring.

 

Duh,.. I forgot you had the 3/8 stuff in there.
I just questioned my own answer..lol!