Alright! I finally got back to poking around yesterday, and I THINK I've fixed the vacuum leak. The line between the manifold and the brake booster seems to have been a size too large. Sure enough, there was a bit of a crimp where it connected to the vacuum check valve at the booster. Seeing it in daylight helped figure that out quite a bit...
Unfortunately I was unable to test and be absolutely sure that the fix is good... Something seems to have died in the ignition system (which has been less than completely cooperative all along). With the exception of the points and condenser, everything in the ignition system looks well loved... To that point, I ordered a complete setup... while that takes its sweet time getting here, I want to ask a few questions to make sure I'm seeing some things correctly.
I believe this is a condensor at the coil:
... and this is a condenser at the distributor...
The distributor condenser is as I would expect it, but the one at the coil looks to be redundant (though it may be the other way around). The condenser is eliminated with the electronic points so it's fairly moot, but for my own betterment I want to make sure I'm not going crazy.
There's also the question of this little guy:
I've looked through all of the wiring diagrams I can get my hands on, and through the various manuals and I'm really not convinced I know what this is. I THINK it's the ballast resistor, which would also be eliminated with the Pertronix setup, but a little assurance would be helpful.
Finally there's the question of this guy....
It's in context with the ignition pieces, and right alongside them in the harness, but again I'm not seeing anything about it in any schematics or manuals... There are two green/yellow wires and a green/red wire... I might be blind, but this is giving me pause.