I just bought a autometer water temp gauge. It came with fittings but I cant find a spot to screw it into. I would say install inline with the radiator hose with a pipe and bung but then that wouldnt be reading the temp of the block/head.

 

That wouldn't be a good place to mount it as the coolant only flows through that pipe when the thermostat is open.

 

I used the stock position on the head. The head has metric threads and the sensor is NPT from the short sweet electrical gauge. I just used some RVT and screwed it in a few threads till it got tight and called it good. 20k on one engine and 10k on another and I never had an issue. If you are using the mechanical gauge, the only way that I know of to get a proper reading is to tap the top hose that goes from the head to the radiator.