I was always under the impression that pinion angle is referring to the diffrence or angle between the front and rear yokes.Stock would be close to zero,probably no more than a few degrees. How much drop on the rear would somewhat depend on how much power you're going to put down, and how much traction you expect(street tires, slicks...), what you're looking for is near zero at full applied power. This number will obviously be different for different vehicles, a slant six with E78-14s will never wind up the rear like a 600 horse big block with slicks, ya know?
There are many variables here, what's your intended use? Street, drag, both? What springs are you running, Superstock, stock slant six or v8, or HD? How much motor? Stick or auto? How much tire? All things to think about...:coffee2: