I found locally a used Ibanez body for a great price. The body is completely stripped of all parts and electronics and a bit beat up, but otherwise perfect for a project. How hard would it be to modify the neck pocket for a 5 string Warmth/Carvin/Mighty Mite or similar neck? It was originally a 4 string. Widening the pickup cavities isn't too big of a deal. My thoughts are that to make a viable parts bass, I need to get a neck fitted to it first. I can then position the bridge by putting all the saddles at the mid point and measuring from the nut to the scale length of the neck and should be able to intonate each string. String width will then tell me how wide to cut out from each side of the pickup cavities to ensure the pickups actually pick up string vibrations. Ideally, I would find a 5 string PJ to modify, as that's the closest "off the shelf" design to what I'm trying to achieve, but the final pickup combination supersedes aesthetics to me.