Pinion angle

The pinion must be nose-down from the driveshaft. The driveshaft is the reference.
In this way, when you put the power into it, the pinion will rise up towards zero. The idea is that at max power, the pinion angle will be between; equal and opposite from the trans angle , and zero.
The more power you have, the higher the pinion will climb. Likewise if your springs are soft, and they wrap up at the front. Likewise if your suspension hooks.
In a streeter it is often better to bias the angle to the small end of the range for smoothness when cruising. Cuz most of the time she'll be spinning anyway.
In a racecar it is best to bias closer to zero angle at full power.