180 degrees is not a problem. With a pressurized radiator, 15 lb cap, and 50-50 antifreeze, it will not boil til over 250 degrees. That is not great for the engine, 250F, but it will not boil. If you have a lower pressure cap, the max temp for boiling will be lower.
Modern engines have better valves in them than the old stuff and the exhaust valve is the first thing to overheat in any engine. If you work it hard, the exhaust valve will be much hotter than anything else in the engine and 20 degrees of coolant temp rise will be something like 200 degrees of valve temp rise.
