Ported vacuum for advance,
manifold vacuum for retard.
Of course you only need retarded spark in a high performance application when forced induction is in the picture...or emission controls-yuck! :p
There are all kinds of things you can do with mechanical systems like bleeds and different diameter diaphrams as well as preload springs for the diaphram(s). I experimented with all these things at one time by cobbling together various types of diaphrams together (what am I nuts?) and I always came back to a plain old adjustable vacuum advance canister like they had on early sixties fords. They are nice to have so you can adjust not only the preload but also the total vacuum advance, great for mileage running pump gas.
Then electronics came along and all that adjustabilty went out the window, thank God for the aftermarket black boxes that are adjustable with a laptop. Honestly trying to keep the facory non adjustable stuff is a waste of time, if you can't play with the spark advance, a plain old mechanical distributor (with electronic pickups) is better than the non-adjustable stuff for power.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”
— Han Solo