Temp gauge bulb install location

[hchad18]

I want to install a mechanical temp gauge and keep the stock electrical gauge also. This is an 85 van small block in a 83 c-10. So the port on the head is for the stock gauge. The port on the intake goes to the heater, and I'm not real sure about the ports on the thermostat housing. One is being used and the other is disconnected. My question is that the port on the water pump is plugged and I believe some motors have that one going to the heater. So can I change the heater hose from the intake to the water pump and use the intake for my temp gauge? Thanks.