The voice of experience -- if this car's an unknown, drive it very carefully to a really reputable shop, preferably one that will listen to you and work with you, and have the brake system completely rebuilt. That is, unless you want to do it yourself, which really isn't all that hard. But you need to do a lot more than simply look at the wear on the shoes -- you should replace all the brake lines and hoses, no questions asked. In fact, the hoses are probably the culprit.
Hoses can let go -- a bad scene. But the more likely problem is that they'll swell up inside, making it hard for the fluid to go through, and this will give your brakes a really funky feel. The lines can let go -- don't ask me how I know. The hole in my garage wall is evidence. The bad place in the lines is just inside that little plate under the driver's door. Mud cakes up inside and the line rusts. Replace them with stainless steel, and your grandchildren will never have to worry about them again. This is not expensive, and not hard to do. The worst is the right front -- wiggling it around all those components on the firewall. The rest, easy peasy, even the rear one.
Cylinders, either rebuild them or replace them.
Master cylinder -- do it, and if there's the slightest evidence of a leak, get that booster rebuilt. In fact rebuild it anyway. Look on the internet for outfits that specialize in rebuilding boosters. I had mine done at a place in Ft. Lauderdale; don't remember the name but they were wonderful. Better than going through a catalog
parts house who does the same thing with a markup.
Once you're done, you're done, and you have the peace of mind that you have good brakes.
There's another thread on this forum where someone was trying to install a dual
master cylinder on his car. Yes, this can certainly be an added safety measure, but these cars have been driven billions and trillions of miles safely with the original brakes. They're fine, as long as they're in good condition.
