Hey, I am wondering how difficult it is to switch PAF's to P90's in Gibson SG's and Les Paul Studio guitars? Are the holes considerably different in size--do they prevent the dropping in of the different shape pick-up. Related--does anyone know if the new SG Classics actually have the regular size p'up cavity--the excess being merely covered by the pick guard? This would allow easy switch to PAF's if true. Someone suggested it might be. Thanks!