IIRC up thru 72 the front disc were Kelsey Hayes 4 piston calipers, the MC (manual brakes) was 1" Dia. (IIRC)
There was a separate dist block and prop valve. The dist block also had the brake warning light in it.
At some point (68,69,70,71,72,73???) they went with a "combo" unit like in the photo of post 3.
IMHO if you have the pre 73 setup complete you are all set. If you have the 73 up you are all set.
Just don't combine the two.
Choose a year and go with it. If your car has 73 up calipers then pick parts for 73 up.
Just my 2 cents
( If I got the switch over year off let me know and I will edit)