mechanical water temp

[killermrob83]

Japanese made '90 Corolla LE with 4A-FE/5spd. I purchased a Sunpro mechanical water/oil temperature guage but am not really finding a location to obtain a water teperature reading. The only thing that I can see might be possible is to remove the fan control switch mounted in the water inlet. At that point I would have to wire the fan to be operated manually from inside the car via a custom made switch and wiring harness. Either that or have a machinist custom make a fitting that I could install in the radiator hose coming off of the top of the radiator and going to the water inlet. Any other ideas would be greatly appreciated.
On the other hand, I would almost rather have a mechanical oil temperature reading instead. I already have a mechanical oil pressure guage sensor located where the pressure switch used to be for the idiot light on the dash. There is a small plug in the block just inboard of that location, between the pressure switch (used to be) and the oil filter. Does anyone know if this is a plugged off oil passage? I thought that I had read somewhere that the
4A-GE engines use this location for some sort of oil pressure reading. Thank you for your time and consideration. Rob