Hello, I want to offer my two cents' worth.  I have seen a lot of cooling system setups, and most often people overlook the volume and pressure that a jet pump is capable of.  If the cooling system is not plumbed properly, it leads to all sorts of problems.  I know with my own outfit, I run a thermostat, and I regulate my cooling water to be no more than 20 P.S.I.  Also, I regulate the water going into the headers, so that there is barely any visible steam.  This works, and has been working for 20 years.  Another important thing to remember is that when you shut off, there should be no water in the exhaust system. How you achieve this, is up to you, but it will work, and regulate the engine temperatures properly, without fluctuating up and down, or getting water into the engine itself. I hope this helps.