I put a Jazz Bass Vintage 63 Obsidian wire harness ( No longer in production) into a Squier VM fretless with upgraded pickups also..( Aguilar Jazz H.C) & there is a considerable improvement...in the instrument tonally but' they are a fiddley installation certainly not a five minute job at all & after lots of F%#!!!!! this & just why the F%#!!!! did i buy that.....i was happy with the finished project....
I did buy all of the replacement parts on the used market.