Yes that will work to disable the vac adv but in my case one of my dists, the phasing was way off so I pumped up the can with a vac pumpto rotate the top plate till the phasing was dead on then drilled straight down thru the 2 plates & pinned em solid in that location

I ended up using one superlight (Mr. Gasket 925B) spring, and the OEM heavy spring with loop.

So it cranks at (estimated) 14 degrees for easy starting where the dist is currently set, idle is stable at 27 deg @ 1200 rpm, gradual advance to 35@4000, didn't want to rev the engine higher while leaning over it with a timing light. Still have the "13" (26 crank deg) slots which may be a bit too much advance at high rpm, although the inherent ignition box retard should keep it below 38. If not I can just back it off a degree or two until I replace it with an "11" (22 deg) piece.

The vacuum advance adjustment I still need to tweak, but it pulls in up to 16 deg at cruise (15" vac) which is also about right.

Now to start tuning the carb until I pitch it and buy a good one from Thumper

I run a Mallory race dist that I got real cheap. No vacuum advance on it and I run about 22 at idle and 36 total all in by 1800 rpm. I usually run 92 pump on the street and racing and have never had any detonation at all. Ron

Have you ever considered vacuum advance? Definitely a good idea for the street

I don't remember your setup - how big a cam, rear gears, etc.?