A low-pressure 235 was used in big trucks from 1941-1953.
I believe the Shop Manuals recommend 0 lbs pressure in small truck engines until 1953; 4 lbs in 1954/55; 7 lbs in passenger cars. I do not know about 55+ trucks/cars or medium/heavy trucks.
4 lbs should be OK, if your radiator takes a pressure cap. I have run 4 lbs in a 54 235 for years - no boil over or loss of fluid.
