Unfortunately regulators dont help much in the case where a pump develops enough pressure to overcome closed carb float chamber needle valves as at that stage theres no flow so nothing to regulate. Many think it will help but if you imagine a pipeline with a closed end that is pumped up to a certain pressure then putting a valve in the middle of it isnt going to make any difference to the pressure however much you adjust its position!
If your carbs overflow and your valves/floats are all in good condition all you can do is reduce the tension exerted by the spring in the pump which is done by packing the body away from crankcase so its operating arm is moved less distance by the cam....