I'd use a 160 degree thermostat not a 180. A 180 thermostat will have the radiator cooling procedure start at 180, can only go up from there. A gasoline engine does not need to be that hot, it's not a diesel. A 160 degree will get you up to operating temp quickly then start the cooling system to maintain what it can above that temp. The radiator works to cool things when fluid is flowing through it, with the thermostat closed it's only cooling what is in the rad itself. With a 180 degree thermostat you are choosing to never have your engine run below 180 degrees once it's warmed up.
I use a 160 degree thermostat and the cooling system, the pump, hoses, radiator, 10 pound radiator cap, fan, shroud, etc, keep the temperature around 185 degrees while running. If the cooling system was a bit more efficient it may keep the coolant a bit cooler, if it was less efficient it would run hotter.
Our engines produce a lot of heat, it takes a good cooling system and a properly tuned engine to maintain that heat.
