It is not hard to change to switch from disk to drum. There are several options available. One of the things people often do is use the swap as an opportunity to install the BBP (big bolt pattern) hubs. Makes sense, but it adds a degree of difficulty.
I have no experience with aftermarket solutions to this issue.
Using Mopar assemblies, the easiest way to install disk brakes on your Swinger is to get the KH 4-piston units from a 65-72 A-body. You'll need the spindle and everything below the upper ball joint and above the lower control arm. You'll need all of the disk brake lines in the front end, the distribution block/proportioning valve, and a disk brake master cylinder (67-72). This will mean you get to keep your SBP (small bolt pattern) wheels. Because it entails taking the front end apart, you'll need a front end alignment when you're done.
Conversion to BBP on the front isn't adds the upper control arm to the shopping list. It brings with it the complication and expense of what to do with the SBP rear. It is a PITA to drag around 2 spare tires.
All A-body cars up to 72 used SBP wheels and hubs. /6, drum brake cars from 73 on also used SBP. 73 and on, with disk brake, cars used BBP wheels and hubs.
