A lower temp t-stat won't help overheating problems. When you say it was overheating, how hot was the temp gauge showing?
Also, FWIW, I'm cammed, running a tuned PCM, etc. and still have a 195* t-stat with no pinging or other issues. And when it's getting up to 225* while hammering on it up a long, steep hill with a trailer in 80* weather, my temp is limited by the cooling system capacity, rather than the t-stat anyway.