I have since fitted ALPHA 250k pots, a better 5 way switch and a set of Stewmack Golden Age pickups (6K neck and middle 7.6 bridge)
Also wired as per this schematic
Very happy with the result. Pickups sound great, tone for the neck and bridge are linked so all pickups now have controls and the 50's style gibson wiring reduces treble loss as you roll off the volume.