Proportioning valve

67 had a main distribution valve in the normal place, not a proportioning valve. If Disc brakes it had a separate hold off valve for the rear just down the frame rail from it. It is sometimes confused as a proportioning valve, often called a Texas valve based on its shape. I suggest Inline tubes for your source if wanting authentic type.

if you want the later combo valve the same source. Just be prepared to do some line tweaking and maybe a new hole in the frame rail and to orient it!