I am thinking of buying a arca-swiss compatible clamp to mount onto my Manfrotto head that uses the rc2 plates. I realize buying a new head would likely be the preferable choice but I am not a professional and am looking to save a bit here. This will bring me into the arca-swiss world which seems to be the standard and allow me to get a nice L plate. I notice there are different types of arca-swiss compatible clamps: short screw knobs, long screw knobs, leavers, both, not to mention levels and graduations and sizes/shapes. What would you be looking for?