the thermostat housing on the original 305sbc I'm rebuilding and was wondering if you can put the 2 sensors in the block or do I have to leave them In the original thermostat housing

 

The sensor in the t stat housing feeds the ecm, the sensor that feeds the gauge, if you car is so equipped is in the head between #1 and #3 cylinder.
If your car has a light instead of the gauge, then no reason you couldn't move it to the head.

 

Thank you, I checked it has a gage no light it's on an 84 ss Monte Carlo

 

so since it has a gauge I can't move it to the head? What about the other one is that one for the fan?Thanks again