The flange on the HEI housing needs to be ground/machined off, and the housing clamp from the stovebolt vacuum advance unit is used to position it at the right height to line up the gear and the oil pump drive. I've also used a split shaft collar machined to the correct diameter to adjust the height of the HEI housing, and a bolt and washer in the original distributor attaching hole as a hold-down.
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!