Double post removed!
 
(Message edited by TerryC on May 22, 2014)

It would take some hunting and some routing, but my 2nd choice would be to make a Berry Oakley Tractor; move the neck p/up to between the bridge p/up & bridge, and replace it with a BiSonic (or Dark Star).
 
Peter

Peter, I have wanted to do that Berry Oakley  Tractor  mod my self.    AND ___ (((((The Phil Lesh EB-3 )))))___  
I have some new old stock Darlington Pair emitters  that  might  be used in such a pursuit for the pending Lesh EB-3 project.  
 
( I just have too many irons in the fire ! ) LOL ___
 
Curtis Novak now has a Bi-Sonic !    
http://curtisnovak.com/pickups/BS-DS.shtml
 
 AND , all such mods could also be implemented on a fretless conversion ( saving this thread from the high jack   )

The Lesh EB-3 would be an interesting conversion since I own one I never play due to the muddiness whenever the neck PU is being used. Where might one look to gather additional information regarding the adaptations/refinements Phil had made to this instrument?