Ok, I got my check valve. I put it in. Everything works great.
But I bought a rebuilt booster and a master cylinder.
Should I replace the booster and mc? Aww man decisions decisions.
I also bought a sway bar bushing and two upper control arms because it would be easier to get them in with the booster out. But now I don't need it out...
So the lesson is check the check valve before ordering the booster.
Well, the car has close to 200k on it. And the parts were cheap. So here goes, I'm going to replace them. Now I sound like one of those cheesy mechanics "I replaced it all because it'll all eventually fail and now you can be secure knowing you have great brakes. "
Oh man. I'm so dumb.