I acquired a 97 Ranger with that problem, no brakes. Replaced master cylinder, rear cylinders, rear shoes, and rear brake "springs and stuff." During bleeding the rear had No fluid leaving the left rear cylinder. Then notice brake fluid "welling up" and out of the "cruise control cutoff switch," mounted to the end of the master cylinder on top. Replaced it (OReileys $28), finished the bleed, brakes work now. That item was my "final fix."
Other possibilities with yours is air or a leak somewhere else that you haven't found yet.