The only thing that really maters is that the tranmission and rear axle are at the same angle. The tail shaft and rear end yoke need to run exacly parallel to each other, simple as that. I think you are making too much of this.
That’s only true if you never hammer the car or don’t mind axle hop.
Ideally, the pinion needs to be angled down a bit from the drive shaft angle 1.5-3 degrees, while maintaining parallelism to the output shaft. Under heavy acceleration, your pinion rotates up. If it goes beyond parallel with the driveshaft, axle hop ensues. The more horsepower and traction, the bigger the problem.
If you raise your pinion to accommodate the lower output shaft on the transmission to keep things parallel, you end up with this problem. You either end up with the wrong pinion axle and axle hop, or a driveshaft phasing harmonic vibration.
I fought this issue in my Charger w/TKO600, swapping a lot of shims to find a good compromise.
