Mechanical temp gauge line routing

If you are running an automatic, you can run it through the oblong firewall hole for the clutch pushrod. You may have to look around, there are ARE smaller pipe thread adapters FOR SOME GAUGES (the special fitting is not standard) You need to mount it low, meaning BELOW the thermostat. Do you run a heater? I have thought about (on a SB Mopar) drilling and tapping the intake where it blanks the rear coolant port on the head, BUT THAT IS FAIRLY thin material. If you try that be careful. I would not go larger than 3/8 pipe which is nominal 5/8 OD

WHAT ENGINE ARE YOU RUNNING? SB? B/RB? Studebaker flathead six? Rolls Merlin V12?