Pinion angle

It's best IMO, to leave them loose and lightly bolted in. Then set your ride height.; front and rear. Then set you angle. And you need to compensate a bit extra for soft street springs, and hi-torque engines, and racing versus street.
To get an idea of how much to compensate, just watch the pinion jump, up on any rear wheel drive car, from no load applied to when the operator locks the brakes,and puts it in gear, and gives it a bit of gas. With street springs it moves around quite a bit ; maybe 4/5* just on that, and you haven't even really put much power into it. If you don't compensate enough, the pinion will go nose up, and then it will really vibrate. I over-compensated and had to install some shims. No big deal.
Some books say 5 to 7, my bulletin book says 5 to 10,some say equal but opposite to the front, when loaded. Really it's almost a crapshoot.
I went 7* down, and later took 2* out because I was not enjoying the steady-state at 65=2200. It got a bit better. My thought was that at 7* I was safe to add or subtract a 2* shim, and it worked out great.