I'm wanting to rewire my Spector Legend 5 classic (w EMG-HZ p/ups) to have a pickup blend knob and a master volume instead of two volumes. I was looking up blend knobs online and how do I know which one i need? There was a 250k, 500k, ect. How do I know which will work? And will I need to get a different volume pot or will one of the stock ones work? I'm also wanting to do this on a passive mexican jazz bass with US pickups. So info on that would be good too.