I had a Super J 5 with super fatty pickups. I changed the wiring of both pups to series. This is super easy, a quick change done in the control cavity.
This gave me a beefier bridge solo sound, and moved the solo neck pickup much closer to Ptone territory. The two blended positions were also better.
A couple series/parallel switches could have been added, but I wanted to keep it simple.
When the split P pickup became available, I ordered it and a new pickguard. The split P located a bit further from the neck, in the usual P bass position. This definitely got evrry last bit of that P bass sound.
I think the pickups are pretty close in sound, and the position made the biggest difference.
I have also put Ptone pickups in the soap bar shape in AB-1’s. That gets more P sound, but because the position stays the same, not quite the whole enchilada.
I have a Super P 4, with the split pickup, and it’s pure P bass sound. With the added twist of the hybrid tone control, which can do a nice scooped sound.
So the p tones are definitely worth it. But there are a few inexpensive things to try with the super fatties or any other four wire pickup that can be wired to series.