Recently installed a Cold Case 2 row radiator in my 72 Cutlass 350.
I notice on the highway at speed, the engine temperature will cycle between 170 and 200 degrees approx every minute . Don't notice same behavior during city driving. Currently equipped with a 195 degree thermostat. I'd like to see the engine maintain a more consistent temperature rather than have these 30 degree swings. Is there something else going on or do I have too much cooling?

 

It could be an air pocket or a faulty thermostat.

 

As said, look at getting a new thermostat.

 

The thermal mass of the engine and coolant can't physically cycle that quickly. You've either got a bad sender or an air pocket.