HEI starts to have spark scatter problems at 5500-5800 RPM unless the reluctor is modified and the vacuum advance is locked out. My "stock appearing" HEI units on the claimer engines would go to 7K without any problems.
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!