Dart with no rear brakes?
... these are original drum brakes.
Then it's very likely you'll need all four wheel cylinders, in addition to the master, and you'll need all three hoses, too, and possibly both rear emergency brake cables.
When I did my 100% original, running, driving car, I didn't immediately change the wheel cylinders (they weren't leaking) or the cables (the emergency brake held the car), and I ended up taking things back apart to change both.
You should be able to get everything in one batch at a good price from RockAuto.
I'd get complete spring and adjuster kits, too (they're cheap!), and shoes if you need them.
You can get the "second version" adjusters, used in many things, including '90s medium pickups, if you don't mind some fiddling to get them to work. They're supposed to be better, but I haven't used them enough to say whether they are.
– Eric