As for the odds, I would say pretty good on any given sunny day here in WA. I see alot of them riding around when we finally get some sun, and have witnessed a low speed crash involving a restored 57 chevy belair and a newer volkswagen. No real damage done to either.
As for age, not in the span the vehicles were made unless there is some underlying rust or metal fatigue. Steel only gets weaker due to environmental attack (corrosion) and repeated stress and strain (driving). Most of those older cars were not beat up enough to cause metal fatigue to the point that it would 'fail' or increase the damage caused to itself in a collision.
