You will get better heat transfer/cooling and more than adequate freezing (-40) and corrosion protection with 50/50. I typically run about 35/65 to get a little better heat transfer. It gives me more than adequate freezing (well below 0 F) and corrosion protection.
The real cause of corrosion is lack of regular changes and flushing.
You also need to think about the time period when these cars were originally built and used. Many people did not use antifreeze at all during the warmer months. Some cars were just drained and not used in cold weather. Methanol and denatured alcohol were used as antifreeze as well as ethylene glycol and glycerin. You car was built just before WWII. You car might even have sat for 5 or 6 years during the war due to rationing of gas, oil, and tires.
Read your owner's manual about maintaining the cooling system. Then you will understand why these old engines have such corroded cooling passages.
