Questions about brakes on a 1969 k5 4x4

[draggin49]

Just picked up a 69 k5 blazer 4x4 . Took it for a drive , runs great , but the brakes are awful to the point of dangerous. Barely any stopping power and don’t engage till pedal damn near is touching the floor.The booster on it is stamped remanufactured , so I’m guessing the master cylinder is as well . Just debating on if I should even bother going through messing with this setup or just replace it with a fresh one . If I replace it I want to use something that will be a direct replacement for what’s in there and not require a bunch of other changes or mount location etc .