Actually, the GM HEI is pretty much idiot proof. Connecting 12V to the Tach terminal doesn't hurt it- - - - -the spark just doesn't happen. Some of the aftermarket electronic ignition systems fry themselves if you sneeze at the wrong time!
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!