14" fan + 360 = overheat

I wouldn't worry about the thermostat. You want to warm up fast and then "stay" at the optimum operating temperature of about 195. That would be accomplished by a better and or cleaner radiator and cooling system. Have you considered taking the radiator to a shop to have it checked more thoroughly and possibly boiled out? Then maybe run a few flush-rinse cycles to get the gunk out of the block as well? Could be as simple as that.

It does not matter how much air you push or what thermostat is installed if the system cannot transfer the heat.