Help Needed reference picture on R3500 dually brakes

[wcstory]

I took a ton of pictures before I disassembled the brakes with a small digital camera I keep in my tool box(.....but I'm screwed....)

Fast forward 2+ months, everything has been sandblasted and painted or powder coated. I bought a ton of AC Delco bearings, seals and brake parts. Time to reassemble...I went to pull up the files on the computer and they are unreadable. Now I cannot find the original SD card to recover the files from. I do have software where I can recover from formatted media on the cards

I have a GM 10.5" 14 bolt DRW off 1989 GMC R3500 C&C. It was a former telephone company bucket truck. I got it without the aerial lift to uses as a work truck. The frame went soft so it got parted out. I'm using the 1989 running gear under my 1966 GMC 1 ton truck. The old Eaton rear is shot and parts are near impossible to find.

Both brake drum backing plates are the same. The passenger's side cable came out to the rear, was secured to the brake line bracket then went to the equalizer on the drivers side. This looked factory and not a backyard hack job.

If the Passenger's side backing plate is incorrect....can I just redrill the plate for the parking brake cable facing forward?

The moderator Hatzie had some great GM reference books and manuals he scanned, but I cannot find the diagrams that show what I'm looking for.