Wondering if anyone can help with info disc brake prop. valve.

I don't know what year those parts are from, but up through 1967 at least the proportioning valve was a separate object from the distribution block (safety switch) which you show in the photo (two different versions). It was plumbed into the rear brake line and located along the frame rail, and it doesn't look like the seller packaged it up for you. Too bad. So if you wanted to use the distribution block provided, you would need to plumb a PV into the rear brake line (this is actually dead easy — no cutting or flaring required — just attach the PV directly to the rear brake line and buy a short length of premade brake line to go between the PV and the distribution block — you can form it into a loop so it all lines up with the factory hard lines). I used a Summit adjustable PV for this application.

The other distribution block shown allegedly contains a proportioning valve (this is how Mopar did it on later models), but I found this created too much rear bias on my A-body, and it cannot be adjusted, so I went ahead and installed an adjustable PV as described above. BTW I had to crank it 75% "down" for proper balance.