[Frank Messina]

Doc,
Everything FWB said X2, plus an aluminum headed engine is going to take a bit more temperature (even up to 200°) to make best power and still be safe from detonation. An iron headed engine on the other hand retains more heat and is more susceptible to detonation if exposed to elevated operating temps for very long. If for some reason you ever do change the thermostat, test it on the stove in a pot of water first to verify the opening point. I've found that some 180° t-stats opened between 192 - 195°. Ford Motorcraft parts generally have been right on the money. I think your 180° is perfect. FWIW
Frank