Here is where to find perches & shock mounts for that axle (I have Chevy blazer s-10 ZR-2 axle in my '50 3600, but I have 2" wide rear leafs because it's 3/4 ton.... maybe these will work for you?). All I had to do was put a bushing in the center pin hole in the perch to get my stock leaf spring pin to fit snugly. They might also have something that will work better that is not listed on the site- they are nice people to deal with, just give them a call.
I used their perches, u-bolts, spring plates and shock mounts- all heavy duty nicely made stuff:
Ruff Stuff Specialtiesps- to center your rear wheels in the fenders, just take your leafs and turn them front-to-back....put the front end of the leaf on the rear mount.