Back to the beginning...
If you want faster gears and modern brakes under a 1 ton AD truck the easiest and cheapest is a nerer 14 bolt rear axle swap from a GM "cab and chassis" pickup (without the pickup bed).
Then if you want front disc brakes recently a kit is available for the original axle. Has been discussed here and or in the swap meet section.
Just because you have whatever given components on hand doesn't make that the best, cheapest, or easiest option.
Consider all options and make an informed decision.
Grigg
