NOS Booster, use or rebuild?

I have run many 50 year old boosters that are nos with no problem. The original one on my 76 440 truck still works like new even with 80,000 miles on it. The rubber back then was leaps and bounds over what is being built today quality wise. Back then they used natural rubber from trees not synthetic made with chemicals. Same for tires. I have 50 year old tires in better shape than new ones. Did you know new tires come with expiration dates? Tire shops won't even mount a five year old tire.