Here's what your going to have to do. First you will have to get a radiator cap that is sealed on the outer diameter of the cap like the newer recovery systems have. Then you will have to put a recovery tank on the fender inner panel with the hose from the radiator overflow to the tank. �Now, if you can do that and guarantee that the radiator is sealed from outside air then the radiator can be filled to the very top of the neck and the cap put on. If nothing leaks outside of the cap the excess coolant will be transferred to the tank and of course the tank will have to be filled with some coolant before that so it has a reserve of fluid. Now, when the engine cools and you have the correct radiator cap (which may be hard to find for our low pressure systems) the coolant will be sucked back into the radiator and the radiator will still be full up to the neck.
Now, as far as I am concerned this is not a practical method for our Jeeps. They were not intended to be that way and IF you keep the fluid level about an inch or two above the cores when the system is cold you will never have a need for a holding tank. The cooling system and radiator is designed to allow room for expansion of the fluid and if your having trouble with it spitting out coolant then your over filling the radiator.
That is a blunt statement but that is the truth. Unless your engine temp is getting to the boiling point with a 4 to 7 psi cap you will never loose coolant IF THE RADIATOR IS NOT OVER FILLED.
