The 410 head, used in its intended orientation (with the bubble level facing the photographer), has the lens axis offset from the centre of panning rotation. Your sliding plate will not be helpful here (unless you also use a panning base, as suggested by Ellis). But if you rotate the camera 90 degrees from its intended orientation, your plan should work. If you don't want a panning base, get a bubble level to place on the lower, horizontal Manfrotto label, and level the rig with your tripod legs.