I'm going to try to update this thread in chronological order and not get too stuck in the weeds with all the nitty gritty details of what has been done in the past years.
First: Brake rebuild
For this all the lines were replaced. I was young enough I do not remember all of the specifics. We got a full kit but had to tweak the lines in several spots. If I am remembering correctly they were mostly the lines near the master cylinder. At this point the truck was manual brakes, drum front and rear. @davem815 could help with specifics and maybe pictures.
Second: Stud swap and GMT800 Rims
For this studs were swapped for the larger '71-72 studs, obviously new lug nuts were needed, then GMT800 rims and 285/75R16 BFGs were installed. To do this the recommended drill bit. (Off the top of my head I do not remember what size, 37/64" sounds right. If you need to know for sure let me know.) Then the studs were installed, shown in the picture I used washers, then I got an actual stud installer to use, no pictures of that. I did have a couple of issues I had were that Dorman did not send all of the correct studs. The threads that hold the rear hub on were cross threaded so that hub needed to be drilled with a hand drill and the studs had to be installed on the truck. And when installing the studs one of the lug nuts stripped out. When installing studs either use junk lug nuts or rotate between different lug nuts.
Part Numbers:
Front Studs: '71-72 Chevy/GMC C20/C30 SRW Studs - Dorman 610-181 9/16 - 18 Serrated Wheel Stud (Multiple different parts numbers will work here as the SRW and DRW should be the same but have different part numbers. The same with the C20 and C30 differences.)
Rear Studs: '71-72 Chevy/GMC C30 DRW Studs - Dorman 610-189.1 9/16 - 18 Serrated Wheel Stud (I am pretty sure these are the studs I went with, I know I went with the longer ones, these are 3 inches rather than 2 - 5/32 or 1 -7/8. This was so that I could run a 1/2" spacer on the rear so that the hub caps clear the rear floating hub.)
Lug Nuts: Conversion lug nuts were needed. This is so that the lug nuts will have the external thread for the hub caps. From what I read the GMT800's used metric lug nuts but there are conversion lug nuts available. I believe these are the ones I used:
https://www.amazon.com/Nuts-Chevy-st.../dp/B009SDA6YA