It's time to do some measuring, instead of a SWAG (Scientific Wild-Donkey Guess) based on hearsay. Remove the distributor, and measure the distance from the intake manifold where the distributor mounts, to the bottom of the slot in the oil pump drive. Then compare it to the corresponding measurement on the distributor. If it's different, machine the flange off the distributor housing and use a split shaft collar set to the proper depth and clamped tightly onto the housing. That's the same way I adapt a GM HEI distributor to a stovebolt six. Those distributors (intended for 250 and 292 engines) are also a little bit short to fit the 216/235/261 engines. Like the Sun test equipment slogan used to say- - - -"We test- - -not guess!"
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!