If it's the 6-cylinder distributor you're working with, the vacuum advance doesn't even comer into play- - - -just loosen the clamp around the distributor housing and put the dizzy anywhere it needs to be. The advance will stay right where it belongs unless you try to move it by unbolting the advance me4chanism from the block.

Just be sure when the points-open part of the cam lines up, that the distributor rotor is under the proper plug wire terminal. I think there might be a situation possible where the spark has to jump either forward or back some distance to hit the right plug wire. That will cause a miss, or a crossfire to the wrong wire as the speed increases and the centrifugal advance operates.
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!
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