I did the dual reservoir update, it was a four day process. Thanks to the "mechanic" that said, "We dont need to bench bleed it, we can just bleed it after it's on..." Well after three days of not getting any fluid to the back brakes I finally just took it off the truck and bench bled it. "Amazing!", he said. All's fine now.
I used
Classic Parts for the updated parts. Mount kit #71-984 $89.95 and #71-201 master cylinder $54.95.
You will have to enlarge/move the hole in the floor to fill/check the new reservoir or fashion another remote way to deal with it.
Barring not bench bleeding the first time, it only took me about 3 hours to take stock stuff off and replace with new stuff.