The radiator level remains constant and I have not added water for at least the last 8 months.
The benefits of modifying a 28 Chev water pump with modern internals, that still looks very similar on the outside, combined with an overflow tank and a very low pressure sealed cooling system allow motoring in all temperatures with no concern about overheating or loosing water.
In addition by running a very low pressure system I can use modern coolant with anti corrosion additives.
I only would panic if I saw green water under the car.
Cheers
Ray