So I just finished putting in the new fan clutch and thermostat. Found a few more things that more than helped contribute to the overheating problem. Pulled the upper hose to find that the thermostat was in backwards, and got some sediment when I drained the radiator. So block flush, heater core flush and radiator flush also ended up being the other order of the day. Was also going to change the oil, but got too hot. For a another day, I guess.
What amazes me is that it NEVER overheated in traffic until a couple of weeks ago. I’m not going to fault John, the previous owner, as I have done the same (reverse installed a t-stat) thing before. I should say the owner before Dad.
Oh well, all is good and she now has the right clutch as well as some added maintenance, and she runs cool now.