The distributor in the picture is the "tall cap- - -tall rotor" design, which was specifically produced to minimize the possibility of flashover from the rotor tip with 12V ignition systems. If the short cap- - -short rotor system is used with a 12V setup, and the side connector has a taller than normal terminal lug, a flashover is very likely to result. Electronic ignition systems can also develop secondary voltage that was completely unknown in the 1950s. The miss it causes can be extremely difficult to diagnose without an oscilloscope and a very skilled technician operating it. Not a WAG- - - -I've seen it happen on occasion.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!