The factory mounts are pretty close to pointing the pinion 5 degrees up. The spring itself has a nose down angle where the housing bolts. best way is to leave the perches loose. Bolt the housing in on the loose perches. snug it up. Then pap th enose of the pinion with a soft face hammer to get the angle where you want it. You may also want to offset the housing right or left a bit to center the wheels in the wheel house. Mopars are notorius for the wheel houses to be off right to left. Usually doesn't take much. A 1/4"-3/8" can make a world of difference in clearance.
Doug