As my ignition/carb issues resolved now it's time for cooling system. I checked coolant for boiling point and it is very low, around 210 (looks fine, green, regular coolant smell), my truck is 265 so I know the measuring device works properly. So it's time for replacement. As I took hoses off I also found out it has 180F thermostat. OEM should be 195F but it seems like they sell from 160 all the way to 200. Should I go with 195? No rust inside radiator just some crud from silicone gaskets and scaling. Lower hose engine side is very rusty on inside and outside (is that a water pump?). Is that usual rust spot? Radiator has no leaks, should I clean and keep using it? Is there's a drain on the engine block? Just draining radiator I got about 1.5 gallons.