Ideally, I would recommend you set the car on scales. However, if the car is pulling right, it usually means the left tire is planting harder, driving the car to the right. Some additional "pre-load" on the right side will often correct this. On a 4-link, this would be done by shortening the top bar on the right side. Since the bottom bar on the ladder bar is the adjustable one on most ladder bar setups, I would lengthen it about 1/2 turn.

If the car is setting fairly level to start with, this "pre-load" may cause the right rear corner to raise up slightly. In turn the left front will drop (I would take ride height measurements at all four corners before making adjustments). Tightening the left torsion bar will correct this, and in turn add a little more pre-load, which is why I would only adjust the ladder bars 1/2 turn at a time.