There are some very good reasons Chevy chose to go to a taller distributor cap and rotor when they switched from a 6V to a 12V electrical system. I don't believe the short cap distributor was ever used on a 12V system, at least by the factory. Trying to detail the differences will simply create a big fire hydrant watering contest. Suffice it to say that I won't use a short cap setup with 12 volts.
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!