So I've run a boatload of Sea Foam through it, in the fuel, in the oil, spray directly into the carbs. I retested my compression and it's at 120, 120, 110, 120 across the board now. The original results were around 90, 90, 60, 90, then I added some Marvels Mystery Oil and it came up to 160,160,90,160.
I cleaned out the master cylinder with compressed air and then topped it off with brake fluid. Tried bleeding the brakes the first day but couldn't get it working. Went to give it more attention a few days later and it looks like the fluid did some of the work for me as I was able to bleed the brakes. They aren't great, but they are good enough to do a short test drive which is more than I've gotten to do yet.
Took it for a spin around the block and noticed something odd - the rear brakes work when it's off the center stand, but they don't when it's on the center stand. Is this normal behavior?
I gotta say I'm thrilled that I've made it this far this fast.