I got the drum/hub assembly off and checked on the brake adjusters. They were seized up nice and tight. I started with a hammer and a dull cold chisel (after a good soaking of liquid wrench). I ended up busting off a couple teeth from the adjuster, so I decided to stop and do something smarter and more methodical.
As it turns out, removing the shoes made enough room for me to fit a wrench on the adjuster star. A 12-point 1-1/16" fit OK--I think a 26mm would have been better, but I already had the standard wrenches out. With the wrench, I was able to wiggle the adjuster back and forth until the penetrant worked in a little further, and I eventually got them out. All cleaned up with some anti-seize, and I was in business.
I also figured out after consulting the manual that the shoe springs were NOT installed correctly. This explained why the shoe and adjuster had a 1/4" gap before I got started, and the shoe was not being kept tight to the adjuster properly.
The bad news is, I still have a lot of pedal play. All the drums are adjusted, but it still takes 1-1/2 pedal strokes, then it's firm as can be. I've bled this thing to death, and am getting sick of it. It really doesn't quite feel like air in the system anyway. It doesn't get progressively firmer as I pump the pedal, like it usually does when you're compressing air bubbles. Instead, it has absolutely no pedal resistance for the first stroke-and-a-half, then it suddenly has a firm pedal.
I'm half tempted to bypass the hydrovac unit. I understand MCs and vacuum boosters and how they work internally, but I'm not familiar with the hydrovac. I don't trust it either. I'm not real crazy about the idea of an extra cylinder in the system anyway.
I really wish the brakes would have been road worthy after the drum adjustments, because I have a nice big load of limbs to dump 1/4 mile away!
Oh, and to add insult to injury...
It wasn't until I was putting the drum/hub/bearings back together that I felt relative movement between the drum and hub. I have slide-off drums, but I took everything off in one piece! And that sucker was heavy!
I could have sworn that I read the hubs won't slide off somewhere. I guess I got it wrong.
Here are some pics of the brakes coming apart. I know I could've made use of them before I got started...
Brake pics 
