Coolant temp probe in radiator?

No, you won't.
In my experience your gauge will read 10-15 cooler than the motor is.
If you don't have any other way of doing it consider a thermostat housing with the threaded port/s for that.
That way the sensor will see the temp right as it comes out of the block.

Advance auto parts carries these, so I suspect other common stores do as well.

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