The good news was that the motor and transmission was in good shape, with 9,000 miles on the odometer. The clutch plates were stuck, but about an hour of rocking the bike back and forth with the bike in gear and the clutch lever pulled finally broke them free.
The carburator was beyond redemption -- the idle circuit and air bleed were too corroded to rebuild, but an ebay carb took care of that problem. I also replaced the horn, the ignition switch, and one of the rear shocks -- again, using ebay.
So, my instructable is focused mainly on rust and corrosion removal, which took the better part of two months to complete.
Step 1: Removing stuff
I began by removing the seat, gas tank, fenders, exhaust system, side covers, and the rear view mirrors.
The seat was held on by two nuts, and once removing these I simply lifted up the rear of the seat and pulled the front loose from its bracket. With the seat removed, the gas tank (after removing the fuel line) pulled free from its front bracket.
The front fender was held by three bolts, which I wound up having to twist off (too corroded to come loose, even with plenty of penetrating oil). I drilled out these broken bolts.
The rear fender was held on by four bolts, and once removed I could get to the bolts that held the tail light/license bracket. The wire for the tail light unit simply unplugged from the wiring harness.
The exhaust system surprisingly came free without breaking any of the studs that held it on.
The side covers were designed to simply pop on and off, so they came off easily, and the rear view mirrors unscrewed from their handlebar mounts.
Throughout all of the disassembly process I carefully kept track of all loose parts by putting them in labeled sandwitch bags.