Pinion should be nose down relative to the driveshaft.

Are you saying your tailshaft is down relative to the driveshaft? Is this from a lowered car? Usually a driveshaft is down from the transmission.

You said the pinion is almost straight to the driveshaft. 3 degress is not much at the other end but if your goal is no vibration. The answer is matching angles. The less the better. Since I agree zero is not good for universal joint bearings. 1 to 2 degrees max.