They weren't 'conversion' necks. They were OK if you were making a baritone from scratch, but whilst the scale length was correct, they didn't have the extra frets/extra neck length needed to just drop in on a standard body. A 27" bari conversion neck on a neck would be 1.5" longer than a 25.5" scale neck normal, as all the extra scale length has to be taken up in the neck (so you typically end up with a couple of extra frets). The bari necks PB sold had the standard 21 or 22 frets (I forget which) and were only about 1" longer overall, which meant that the bridge needed to be set back by 1/2" to compensate.
Fine for a scratch build body where you could position the bridge and pickups accordingly, but not for a standard body. Obviously this was far worse on the 30" bari necks, as again, these were not the 'conversion' type.
So I think they've been removed as too many people were having issues when fitting them. If you set the bridge plate back as far as it would go, maybe with some extra routing, you might just get it intonated, but quite a lot of people either failed to intonate, or else didn't bother and played out of tune up the neck.
One of my 3 basses has a 27" scale so I might just mod that instead.
It does have an interesting sound, a bit like a brighter JB/PB hybrid having those style pups, the nut is plastic and far too high so the whole thing needs work anyway.
Being a freebie and a bit of a no name it makes a logical platform for experiment.
Probably be like a Teisco and worth heaps in a few years time