I'd stick with 13"x3.5" brakes, the largest brakes available. Given that shoe size there are different drums that fit them, see this post
https://www.stovebolt.com/ubbthread...-14-bolt-axle-swap-info.html#Post1249918Not sure what size drums and shoes (and backing plate?) you have now, but probably worth getting the 13x3.5 if not already.
The shallower drums (see pictures in above link) will be the better choice, leaving more room between backing plate and leaf springs. Bendix # PDR0619, GM # 18006042, NAPA # 440-1651, is a drum with same 13x3.5" brake size but no more offset than necessary.
The difference in a Single wheel 14 bolt (from a pickup truck typically) and a cab and chassis dual wheel 14 bolt (usually a step van, RV, or service truck, no pickup bed) are the hubs used. I believe you've figured this out. Swapping the hubs from the dual wheel axle on to the single wheel housing results in a narrow enough axle for our old trucks (same as the C&C axle width)
Difficulty is the brake backing plate doesn't bolt on in the correct location on axle tube.
Your job is to correct that, more or less move the backing plate flange and weld it back on.
First figure out what brakes you want to use and measure from flange on the hub to backing plate flange on that original setup and duplicate this measurement on your axle/hub combination. Again, see notes and pictures in above link.
