This goes into for what its worth department!
I had a 1966? 2+2 E type in Denver (Mile High, lower boiling temp) with air, that I could never bring into normal temp. Finally hung a RACING oil cooler (About 10X12 inches) in the number 3 slot behind the radiator, condenser and then the cooler. The piping was through the large oil filter an back again, as I remember. 3/4 inch hosing because the six pumped 30 gals of oil per minute.. The results were dramatic. Normal temperature, with air, in slow or stopped traffic. It was explained to me that the six was a thermosiphon engine and cooled primarily by oil. Its been a long time ago, but I do remember the filter was a large removable can that I braised a fitting to and then went back to a place near the filter that took a fitting without braising. I am unsure of the car build year, but I know the motor was a 4 Liter. six cyl.