Cool truck and welcome from Texas.
Why not start with a 2500HD? Buy a RCLB or ECSB that needs some love. It will already have the 14 bolt rear axle, the 4L80e and a heavy duty transfer case, besides the larger and more robust brakes. You will just need a regear based on your tire size, but there is plenty of aftermarket support for the 14 bolt. Looks like the ORD kit works on the 8 lug GM pickups. Not sure if there's a kit out there for the 6 lug?
01-10 2500 and 3500 Chevy Solid Axle Conversion Using OE GM Front Springs For stock (non-lifted) '73-87 GM front spring.
www.offroaddesign.com
Just a thought... Subscribed for the build.