I have an old Framus Texan 12 string with a bolt on neck. I need to reset the angle on this neck and am unsure how to do it. Do you just shim the neck to get the angle correct and if so, what do you use for shimming material? Do you shim with wood, metal or some type of plastic and what type of wood (oak, maple, etc?) metal (stainless, brass, etc?) or plastic should you use? Thanks for your help.