Try Vintage Air
http://www.vintageair.com/catalog.asp
Page 72, 192 degree on
Also S-W sells one, #83304, 200 degree on
The Standard catalog at your local parts house has pages of specs sheets in the back, thread size, temp range and terminals.
I'm not sure that the intake manifold, just behind the thermostat is the best place to put the switch. Kind of at odds with what the thermostat does. Lower part of the radiator or the outlet tube might be better.