Thermostat or not

I have a stock 273 running a 195* thermostat. It runs fine but after a while in the Texas heat it creeps up in temp on the stock guage to 3/4 towards HOT.

My question is since I have bypassed the heater core and live in the heat belt should I run a 180* thermostat or none at all? Pros and cons would be helpfull. I don't want to overheat the motor.

All new hoses and water pump by the way, Stock fan and shroud. As long as I am not running in the heat of the day she runs in the middle to less than middle of the stock guage.

John B.