Hey Brian,
I'm gonna be doing that myself very soon. I've rebuilt the master cylinder before but that was many years ago. I don't remember it being too difficult to remove and if you get under there it will probaby be self explanatory. These old trucks are pretty straight ahead. I love it!!
My advice is:
1. If you have doubts, take pics before you start
2. Take pics and notes as you go if you think you'll need 'em.
3. Save and label all the old parts
3 On the brakes themselves, do one side at a time so if you need to see how something goes back together you can look at the mirror image on the other side.
4.Get a good set of flare nut wrenches so you don't round off any fittings
