I am one of those supposedly "not ideal" proponents of cool running FEs. I have been running 160 degree thermostats in my FEs for 45 years, in everything from the nearly stock 390 in my 74 F350, that I owned for 26 years, 24 of those years with a ball honed std bore low compression 390. I sold that truck 10 years ago to a racing buddy, and as of the end of last year, it was still running fine. In my several street strip 428 CJ Mustangs, Cobra Fairlanes, and my current 59 2 door sedan, I usually see coolant gauge numbers of 160, to 180 (on hotter days), while driving, and it can climb up to 200 or a bit higher if sitting in traffic congestion for 10 minutes or more on a hot summer day, but it drops back down fairly quickly once it gets moving again. In addition to the better performance with a cooler running engine, I like having a "cushion" if I get stuck in gridlock. Maybe the performance of a factory late model computer controlled EFI engine, that is designed to run at well over 200 degree temps, doesn`t suffer much, but a 50-60 year old carbureted was not. Between vapour lock, fuel percolation, slow cranking to start such a hot engine, with a tight engine compartment, I will stick with running my engines "too cool", which has served me well for decades. As for the temp vs wear chart shown above, it looks pretty level from about 160 degrees upward, pretty sure that chart is showing how really cold temps , like starting a dead cold engine in freezing temperatures, is likely to cause increased wear.