So, I tested the Stanza vacuum advances. They are not identical (of course). However, I heard that Hitachi vacuum advances are adjustable so I went ahead and drilled out the sealant to see what was inside.
It seems like the outer screw adjusts the rate of advance, while the inner screw adjusts the total advance. Unfortunately, the first "step" seems to be non-adjustable. For instance, you'll always have 4° at 13.3 kPa regardless of how you adjust the screws. Either way, I plan to mess around and see how close I can get using the available adjustments.