I have been playing the bass for 2 years now. I really just play and study music and don't pay too much attention to p/ups, strings, etc. However, I now would like to get a new set of Rotosound Jazz Flats. My very basic question is when do you want to buy Long Scale, XL Scale, etc. I play a 1980 Fender P-bass. Any advice/info would be greatly appreciated!!!!!