I have an old Jazz bass copy that I want to put a real jazz bass neck pickup in. As the bass sits now the pickup cavity is 4x2 inch and 1 inch deep hole in the body where the pickup would go. Now do I just use a jazz bass pickguard as a guide and just mount the pickup by itself with nothing supporting it. Or should I plug the hole and route a proper pickup cavity. If I do this how deep should the routing be? What effect does not having wood around the pickup have?