63 Dodge Dart, now let me see;)

That’s the rear end I have on the shop floor . It’s been rebuilt and is a cone type “posi” with 3.21 gears .

As for disc brakes you could go back to that donor you got the rear end from and grab everything the upper control arms , spindles, lower ball joints and bolts ,rotors,calipers .
Oh and a set of 15”wheels to make it a roller .
Depending on the condition of the bushings and upper ball joints you should replace them .
BTW I have a new set of lower ball joints for your project that you can have .
Also grab the throttle pedal and cable from the donor .

As for headers Doug’s has a set of shorties that should work .

The 63 is a one year only for the back window and trim, wiper motor ,linkage and firewall .
If I recall Lokar makes a cable type trans throttle pressure set up . They also make a floor shifter for the 904 as do several other companies.

You might want to consider a set of aluminum heads and manifold to keep the weight down so you can stick with the stock manual steering . It steers very light although 5 turns lock to lock . Ferm Feel makes a faster ratio box but it will be heavier filling.
Borgonson makes a smaller p/s unit the should work with the Doug’s shortie headers.
JEGS has a p/b unit for your Dart .

Glen