The front can be converted using what we call the GM conversion. There is plenty of information already posted about it. I would start with the pre-written tech article you can find on the left of this page. It will work with either the original dana 30 front axle your truck came with or the later model dana 44 if one was swapped in.
Rear axle is not based on engine. Based on GVW package. And as mentioned generaly don't need disks back there.
That will just add capacity and does better at stopping straight. Still will have a heavy pedal (that is the manual brakes). Going to power brakes will give a lighter pedal pressure, but will also magnify and issues you have with the brakes. Even then power brakes come in a couple of different versions. for the most part vacuum brakes are almost never used anymore as we found the hydroboost works so much better.
That should be enough to get your research started. If you need any details filled in we know those too.