First suggestion is to learn to use the search function. If you can type a new thread title you can do the same in a search and often find your answer quickly.
As far a dics brakes goes here is a start.
http://67-72chevytrucks.com/vboard/s...68&postcount=4
But realistically buying a truck for a few parts isn't often a good choice. Lets face it calipers, booster and master cylinder should be new or rebuilt and hoses need to be new. Rotors are often worn to or below service limits.
Most old truck front ends are dead as far as wear parts. If you need new stuff buy new stuff.
Upgrading the steering system for the disc brakes is a good idea, GM did for a reason. But a lot of people just adapt with custom parts then put on heavier wheels too.
Basically you need to spend smart not cheap.