I'm guessing you are going disk in the front and drum in the back, I would try a four door sidekick master, the 87 should have the brakes in a x config. so your left front right rear are on the same cup(line) on the master, I would swap the lines under the passingers feet area and look for a proportioning valve from a 1990-1995 samurai for the rear to have one brake line, that should give you a big start.