You'll have to have the drivetrain installed & the car level & the Dana moved laterally so the wheels are centered equally. On moving the Dana rearward be sure & mockup & check the rear shackles & you want the bottom end of the verticle shackles to point somewhat rearward & with that in mind you can only go so far more to the rear. Then you tack weld the perches to locate them then dissassemble & take out the springs & complete the welding. On the angle you could weld them at the std A body angle for a marketable commodity if you ever resell it & use shims if needed to get the angle right or if the trans is ie 3 deg "UP" then you'd want the Dana 3 deg DOWN plus an additional ~2 deg down as the pinion rises on accelleration so you end up with the trans & the Dana parallel but in different planes. I dont have the final word on the angle situation so wait for others with more knowledge to chime in