Really depends on what you want to do. There are aftermarket kits out there that allow you to convert to disks from drums with your current spindles, although be aware the kits are different depending on whether or not you have 9" or 10" drums. And personally because of the lower ball joints I wouldn't use 9" drum spindles for anything, but that's just me. Those kits usually have both the 5x4.5" and 5x4" bolt pattern if you want to keep the original small bolt pattern. Scarebird, Wilwood, and SSBC all make kits for drum spindles.
You can also swap to the later 73+ Mopar disks, which can be done with all factory parts. But that swap requires changing the spindles and either using a tapered ball joint sleeve or new UCA's.
There are a ton of brake swap threads on here detailing the pros and cons of various kits, the search function is your friend!
