That's a converted four string. Tonewise a real monster. It needs some "universal" tube amp (here something hiwattish) and cabs woring both as bass speakers and as guiter speakers, i.e., TL606-alike or TL806-alike cabs and spekers compatible to the EV 15L or EV12L. In my case Oberton 15L400 and Eminence Delta 12A.
Take a cheap chinese Precision bass, 6 cheap chinese tuners, a cheap chinese strat bridge, a cheap chinese firebird pickup and a Di Marzio Model P spilt coil. Some cardboard to cover the head after closing the holes of the tuners an redrilling new (smaller) ones. Some birch plywood (2mm) to make the new pickguadr (the original was initially stiil in use. Replace the nut by a bone nut and cut 6 slots for the strings. Add a set of "LaBella Flats for the Hellcat 6" and tune it like a bass VI. You might notice that i also moved the strap holder to achieve a well balanced instrument.
I think i had already posted pics of the conversion in one of my oldest threads.