Gotta say,, this is, and has been, an interesting thread. I applaud you guys who make the disc conversions to the 400 platform, with having to use a scan tool for the ABS to get proper bleeding, and then having to mess around with E-brakes, it's gotta be a lot of work.
I mentioned before, that for the use my rig gets, ('97 K2500 Sub, 8,600GVW,) that I didn't really "need" discs, and their is a lot of work and cost involved.
I'am actually thinking that, (for me,) an easy way to up-grade the brake system for little money/time, and effort, is to just pull-out the 14SF with its JD7 brakes, (13x2.5 shoes,) and replace the rear end with a 14FF that has the JB8 brakes, (13x3.5 shoes).
This will give 40% more braking effort in the rear, (that's a lot,) and the E-brakes and the other stuff should stay the same.
Ya know, It's almost unknown, but Chevy did have an RPO for a 1ton Sub, (9,200GVW,) I've seen one, it was a factory '96 with the 14FF, JB8,, and the front suspension, brakes, and transfer case from the 9,200GVW pick-up,, kinda rare, the one I saw was an ex Forest Service vehicle.