68 Barracuda 440 getting hot in traffic

It has a 26 inch radiator and also has a a mechanical viscous fan.
There is a fan shroud that has been partially cut at the bottom for some unknown reason so it's not fully enclosed....I bought it that way.
Not sure about water pump and I think it has a 180 degree thermostat.
I drove it about 15 miles on the interstate to a car show today and it ran at 180 but had to wait in line at the show for about 15 minutes at idle when it happened.
It may have actually climbed close to 220.

Run the Milodon High Flow 185 stat and a high flow pump from flowcooler.