I've never used the funky dual-diaphragm on a distributor; think it was only used in '74. I suggest replacing it with a stock single-hose vac adv. can from a '72 (or from a Ford 460 which interchanges too). Ford distributors are essentially the same back to '57 and all/most parts interchange. The single vacuum advance can works exceptionally well and is adjustable for the amount of advance it can provide, by sticking the proper sized allen wrench in the hose bib and turning it 'in'. This changes the vac. advance amount by about 5 degrees per turn. Centrifugal advance is stock-adjustable, too.
As for alky improving your smog test results, that's mostly true. 10% rubbing (or other) alcohol thoroughly mixed in a tank of hi-test, plus having the engine almost incandescently hot cleans up emissions, but will send your Co2 reading to the moon. More than about 15% alky can cause running problems unless you tune for it. More is NOT better!
Back when this ploy was being used, Co2 was not considered a pollutant by CA; dunno about now. I'm expecting any day to read that water is a hazardous, banned fluid in CA because you can drown in it. Good luck- J DeRyke, CA refugee from State insanity