Those were done on a jig at the factory.
What you may want to do is bolt in your springs in the location you want them using the correct front hangers and correct shackles. Set your Dana on the springs with the Spring mounts under them, bolt the housing down with your u bolts and after you put weight on the springs, check your pinion angle. When you have everything correct, tack weld the spring cups to the housing. This way you will have the rear end centered left and right correctly and the pinion angle will be correct so you do not have to run spring shims.
Try to use someone other than the mopar spring cups as the hole in them is way too big for the spring bolts. Your rear end could be off because of this. Not sure why Mopar aftermarket cups have such a large hole in them.