I just switched to an high mass bridge on my Fender P-bass and since the bridge it both thicker then the original and with larger saddles i need a shim at the body end of the neck pocket to get decent action. Never shimmed a neck before, is it anything i need to think off? and what would work well as one? I have heard about using sandpaper, playing cards and such. I only need a pretty thin shim i belive.