I've been wanting a P bass just to play some songs with that classic mid-range thump. 6-string basses don't offer much in the way of old-school mud, and I really miss that from the P-bass I traded. Now, if someone offered a stock 6-string P-bass, there's something I would sell my soul, my car, and part of my finger for...
Any bass with a humbucker at the neck position and a passive setting with a passive tone rolloff should get you there. I've done Queen covers with my LEJ 6'er set that way and it sounds right.
A typical J in series and played thumpy closer to the neck, maybe with some tone rolled off, can get pretty close too, especially once you factor the mix. Like a P pickup, 2 J pickups in series is a humbucker so the focus is on the punchy mids with some highs and lows cut off which, like the P bass, most people hear as a bigger low end even though it isn't.
I loved the fretless P bass I had, but never got into the fretted P basses.