I have a '67 122s also. The system you have is the dual with the front/rear split, right and divorced booster?

Unfortunately, the booster is prone to dying and sucking brake fluid out of the system and (eventually) into the intake manifold.

I plan on by-passing it entirely with a single piece of hard-line.

I understand that rebuild kits for the booster are nearly impossible to come by but complete replacement units are available (not cheap).

Our Peruvian connection has adapted one from some other rig into his 122 but I cannot recall the details.

The bolt patterns are different between the 122 and nearly all later models (with the exception of the drum brake P1800 and I think the very first model year of the rear disk brake P1800). Of course swapping the late disks and calipers will net you the smaller bolt pattern.
No 140 stuff is directly swappable on the '67 122s (for brakes at least).

--
Mike!