i went through this about 5 years ago, I'm trying to remember details.
I have an early 72 built in 08/71. basically it uses the 71 parts.
first there should be no adapters on the brake lines. there should never be an adapter anywhere because it introduces another connection in the brake system and increase the chance for leaks to occur.
This is the correct setup for an early 72 as far as connections, i won't say its concourse correct.
what i noted was, the later 72 after 7/72 they switched to 73 parts. the 73 master has a larger NP connector on the rear drum line. the tubing is the same size but for some reason they made the fitting larger.
a lot of cars have the wrong lines going into the prop valve. the prop valve didn't seem to change during 71-73 all the ones i have seen have the same size connector. so what you can do is order the later prop valve connectors and it should bolt right up.
if i remember at the time they didn't offer a distinction between early and late 72 cars and i had to hunt around for the correct master and lines.
now i went through SCR, Shafer classic reprodutions to get the correct brake lines at the time, i see that now Shafer doesn't list the parts any more for the 71-72 mustang prop valve brake lines. It seems mustangs unlimited doesn't carry them separately anymore they seem to be part of the larger replacement kits.
www.shaferclassic.com
I basically ended up buying 3 different master cylinders and 4 different sets of brake lines to the prop valve before i found the correct parts i needed, without making the parts myself.
there is a lot of confusion on the 72s in regards to parts fitting because they are a mix of 71 and 73 parts, the further along in production your car was to 73 the more 73 parts you got.
for example it was assumed 72 received seat belt warning lights and retractable belts. but all the early ones are just like the 71s no warning light and the belts do not retract in the rear. this also means the use of 71 rear quarter trim panels without the inserts. also early dome lights and headlight switches.