Coolant Temperature

[Lippyp]

Can anybody tell me what coolant temperature (In Centigrade/celsius, not Farenheit, we're modern over here!) my 67' 1/2 ton with a fairly stock 350 (4 barrel Carter AFB) should be running at. The previous owner fitted an electric fan on a manual switch so I am relying on a 34 year old gauge to decide when I turn it on, not a brilliant situation.

I have found a great electronic inline thermostatic control that comes in an aluminium houing that fits in your top rad hose. (Just cut a section out and use it to join the two sections) no problems trying to seal a sensor past the edge of a hose or between rad vanes. It is adjustable between 70 -120 C, what should it be set at?

Thanks