This is an old thread but i wanted to chime in on this since i have an 83 tbird and in case someone stumbles on this looking for what to do.
The 83 has a light on the dash to indicate if you were overheating, i dont recall the exact temp that triggers it off hand but the temp sensor is just a trigger for this light.
What i bought, but have yet to getting around to installing, to bring piece of mind on running temps was an aluminum hose "T" to put inline of the radiator hose and you can install a temp sender for a gauge in it. The hole for a sender on mine is pretty small though but the sender on the digital gauge kit thing i picked up for this is also.