Water boils at 212deg F at atmospheric pressure at sea level. If you are running a 15PSI radiator cap the water temp will have to reach 257deg F for the water to boil.
30 something years ago I was experiencing all the same engine cooling temp issues as you are now. I installed a single 12"? Davis Craig thermo fan in front of the radiator and a KC Laser 95deg C thermo switch into the side of the thermostat housing coupled with a KC Laser thermo fan power relay. In conjunction with the LJ XU1 engine fan blade it keeps the temps under control.