You want a 1967 Impala drum drum (not drum disc) master cylinder. AC Delco 18M1027. No prop valve needed. You can get a two in three out brass block from Inline Tube, or, use your old one and plug one port. On the master, FRONT port to front lines, rear port to the rear line. Not like later ones.
Two doors, four doors, wagons, and ragtops.