(probably idiotic..) question on classic cars/auto shows...

Most vintage guys/collector's just use pump gas. They don't put enough miles on those cars for the valve seats and guides to erode, which is the primary mechanical problem with unleaded. Modern heads don't have the same problem.

You can buy  leaded race fuel  (100 octane or more)  until the end of the year, but it's about 8 bucks a gallon. You can also buy a lead additive at any auto parts store.