Binding, tire clearance at full bump and full articulation turned lock to lock. Steering/trackbar interference at all angles and positions ect. And depending on what type of 4 link you are running, you will want to check for rear steer and tire interference at full bump, full articulation ect.
Make sure that you aren’t flex steering a bunch. Make sure that drive shafts aren’t gonna bind up. Make sure the pinion isn’t rotating up or down a bunch.
Make sure your brake lines are clear from getting pinched at any point in the travel. If a solid axle swap make sure your front driveshaft clears the oil pan, link mounts etc