It looks like you've got about a 6" lift, with some 35's, probably on 16x10's? Do you have any wheel spacers on the rear?
Reason I ask is I swapped a 1-ton rearend out of a Chevy Van and put it underneath my old '90 Suburban. Just had to weld in new spring perches (after cutting off the old), and making sure shock mounts were in the right locations. Installed a 1-ton-to-half-ton crossover u-joint, connected the brake lines, and was good to go.
I'm thinking maybe you could find a one-ton rearend out of a 2000-2006 truck, and upgrade to disc brakes while you're doing the swap. Some 8-lug-to-6-lug wheel adapters (2" thick), and you'll have a wider, more stable stance, too.