The biggest problem with most of those rear disk setups is the loss of parking brake. Even with the Eldo calipers (with a little cam-lever actuator), it doesn't provide positive control. And if you wind up on a steep incline, that could be disastrous.
I haven't got it done yet, but years back i bought a bent AM 11.5 out of a early 2000s 2500HD. I cut the tube ends off to provide donor parts for upgrading a Corp 14 FF to disks. The difference is, these have an integral drum brake inside the disk. And as my '02 2500HD can prove, the parking brake will hold as well as anyone could want. I'm starting a build on an '85 Sub, and it will get a rear C14FF I have on hand. If and when I decide to install those disks, I'll post some pics, but with the entire tube end providing everything I need, the only issue I see is getting the Sub cables hooked up and working with the AAM hardware.