72 C10 rear disc conversion and axle swap

[72HawaiiBlue]

Hey guys

First post here. I have a 72 C10 and I've been wanting to swap out my open differential, 3.07 geared rear axle for a posi unit, and bump the gears up. What are your guy's opinion on 3.73 vs 4.10 I have a 700r4 swapped in already. I have a guy that can get me killer deals from junkyards so I was wondering if there are any later model vehicles that I could get the whole 12 bolt out of and take the ring, pinion and carrier out of to get the posi and higher gears, but maybe also find an axle that may have rear disc brakes as well that would swap onto my original 12 bolt with drums. Any information you guys have would be greatly appreciated.