There's a wealth of information on the suspension part of this message board:
https://67-72chevytrucks.com/vboard/...splay.php?f=25
With that said. I used the CPP blocks. They came with the blocks new U-Bolts. Since I also used 4 inch drop springs for a total of 6 inch drop, I needed to adjust the pinion angle with a 3° shim.
The installation is pretty straight forward, basically remove(or cut) the old u-bolts off, put the spacer in and put the new u-bolts on. The new u-bolts came with nylon locking nuts, so I didn't get too crazy with the torque.