I've never owned a "pure" P bass - lots of basses with a P pup but not that alone...
I'm sure I must have played one at some point in my life but can't recall when.
I had a Westone Thunder 1A which had P bass pups...does that count?
For a Bass you can't go wrong with the luthiers on this forum. I've had two custom builds from @Andyjr1515 and he's also renovated a couple. Check the builds threads to see whose work you like.
I'd also give serious consideration to ACG - Alan builds superb "not quite run of the mill" basses - build quality is amazing and prices are less than a new Fender.
If you're after an Electric Upright you should check out ForteVio who makes electric violins/cellos and double basses. Videos on YT and FB.
Absolutely - I had an amazing sound from my AH150 through a Vanderkley 112 EXT - shouldn't have sold the cab - I blame that eternal search for the "perfect tone".
If you want to borrow a head, you know where I am.