Thanks for your replies.
edwardofhuncote, that east-meets-west conversion sounds intriguing, i'd like to explore that further.
Mica, here are pictures of the bass and control cavity. Any further suggestions about to what is doable and what is practical are greatly appreciated.
I might mention, this bass sounds awesome as it is, i keep it strung with thomastik flatwounds. it's got that acoustic bass growl that's hard to beat. But... years ago i owned a '76 series I fretless. The sound of that bass was an order of magnitude above this one. Since series fretless basses are hard to come by, i'm trying to live within my means and i really like this essence. So that's why i'm exploring this electronics upgrade route. it may not pan out, in which case i haven't really lost anything and i still have an awesome fretless bass. So without further ado, here are pictures of my 1995 essence 5-string fretless, S/N 95K9548: