Mallory Distributor
I too am running triple DCOE's, and have the vacuum port blocked off on my stock distributor. The car just screams... couldn't want any better.
As far as the Mallory, I just bought a Mallory dual-point, centrifugal-only advance distributor for my beloved '39 Ford. Same issues... running multiple carbs, not enough vacuum to drive the stock vacuum-only (no centrifugal) advance.
As far as I can tell, the Mallory has improved performance on the Ford but marginally. However, I have to say I was very underwhelmed with build quality and documentation (non-existent) with this Mallory unit.
The distributor came in a box clearly labelled "Electronic, magnetic pickup distributor" which caused me great alarm, since I'm running 6Volts positive ground on the old Ford, and hence all electronic ignitions are out of the question.
However, when I opened the box, sure enough, here was a mechanical-only, dual point distributor. But, get this, even the permanent metal label on the side of the distributor said "Electronic, point-less distributor" or something to that effect. Interestingly, they managed to slap a one-page sheet on how to adjust advance for a Ford Y-block engine (not mine), with procedures that had no application to my distributor.
finally, the construction of the unit frankly smacks of "built with parts from Ace Hardware"... the original 1939 distributor made this thing look like a piece of junk. But... it works. I can't wait to replace the dual points at $15 a pop. All in all, I not a big Mallory supporter at this point.
Back to your issue: Why not retain your original dizzy, then add one of the MSD units which electronically controls the timing, and is adjustable? This will be much cheaper than the $500 or so I saw quoted for the Mallory unit, and you'll have the benefit of the boosted spark, plus infinitely adjustable advance curve?