I asked Dr Diff the exact same question, his reply

THEORETICALLY, IF YOU LEVEL THE
PERCHES (44 ON CENTER) WHEN THE PINION IS POINTING UPWARD 8 DEGREES,
THE REAREND WILL BOLT IN THE CAR WITH A STOCK PINION ANGLE.

I had the rearend in the car with desired angle before welding.
Might as well get it exact.