I'm with Scott. Bone stock power 71 system is more than adequate for a 71 C10 - just add the booster and you'll be very happy. I'd buy all the booster, mounting brackets, hardware, braces, rods, etc etc from someone parting a 71/72 C10. May want a new booster, but they are easy to swap out if the old one you get from a parter happens to be bad. You MIGHT need new lines from the mc to the first block, but might not. Don't quote me, but I think you might need a new master cylinder - seems I recall the piston hole depth is different between a power and manual mc. I'd confirm that though, might be able to do without changing the mc, might use an adjusted rod length between the booster & master, but I like to use exact factory parts when it comes to brakes so I know if it's not working, it's me and not the design..
(for a change)