Tired of junk thermostats. Going with NOS. Do I need to drill a hole in in?

Makes me wonder if your temperature gauge is out of calibration. Mine in a '72 Valiant is and I saw another person on here complaining the that the engine ran too cool after repeated thermostat change-outs. That's what I thought mine was up to, but after changing the sending unit, testing the thermostat in water and running the engine with a candy thermometer in the radiator, it became evident that the engine was running right at 180 degrees instead of the 160 the gauge indicates. I'm not taking it apart to swap the gauge.

I think the folklore about thermostat quality is up there with motor oil. I'm using an NORS Stant I picked up from eBay. No hole. Works great.