If the material at the radiator is not ready to fail. Then try a new hose and see if it leaks. They seal rather well on rough and pitted surfaces. On the pump and housing the same thing applies. I use a bit of Vaseline to help slip the hose on and have no issues with corrosion. Just wipe it in the hose and slip it on. If the hose connection leaks then worry about it. Modern hose material and good hose clamps help a lot. I have never had a hose leak because the fitting is too pitted. It might happen but..not to me yet. If the outlets on the radiator are failing try to find a "good" radiator shop to replace them. I think the thermostats are the same size for all 216s. And all 235s. So just chose the temp and put it in. I like a 180 for most applications and remember to look for a "vent" hole on the thermostat. If it is not there drill one. It helps a lot to get the air out of the system when you refill it with coolant. When I fill a potential leaky system for the first time I use plain water. That way I don't worry so much if it leaks. Antifreeze is Not good for animals and the environment. Water is safe but the stuff that comes out is who knows what.

Steve H