Thermostat temp has nothing to do with overheating, so you need to choose one based on your driving.
Cooler stats can make a few extra hp, but it can come at the expense of shorter oil life, fuel wash in the cylinders, etc.
I personally have a 195 in every SBC I have. I would much rather give up a couple ponies for the health of the engine. Remember that overheating is when the coolant boils causing major hot-spots. As long as you aren't boiling (or making enough pressure to blow hoses and radiators), hotter is often better.
A little thing to consider: Coolant doesn't really care what temperature it is. As long as the "heat in" (combustion heat) is less than "heat out" (radiator), the temperature wont rise. That condition can happen if you're using no radiator cap and pure water (as long as the temp at the cylinder head doesn't rise above 212), or a 15 lb cap with 50/50 and 265 degrees.... or pure glycol and 300 degrees. As long as the cooling system is able to remove more heat than the engine makes, (and no boiling has occurred) you won't have any issues.
Drivers like the engine to run cool. Engines prefer to be hot. Thermostat temperature has nothing to do with cooling - only the temperature at which the cooling starts. As long as the cooling system is able to remove more heat than the engine makes, the temperature is irrelevant to cooling. Pick the stat that suits your driving.
Race? No stat. Hi-po street? 160 might give you a few more ponies at the expense of oil health. All street? 195 will give up a few hp but may improve the overall health and lifespan of the engine.