I feel Dimarzio Model Js are sort of that pickup. I have them in my MJ-4. Had to squeeze the foam way down though. They're a bit taller than normal.
I suspect you're right about that, because DiMarzio's Model P sounds very close to the MFD split-coil from the SB-1 and SB-2.
If you want some MFD vibe from a J-bass pickup, I think Bardens are a good option. I used some in a Fender Jazz V for awhile, and I thought they sounded like two thirds conventional J pickup mixed with one third MFD humbucker.
A couple of weeks ago, I got Nordstrand Big J Blades (Warm & Wooly) installed in my Sandberg TT-5, and they have tiny hints of MFD vibe as well. Maybe it's the ceramic magnets, but whatever it is, they brought the Sandberg's tone a little closer to my M-2500. Or maybe it's just that their even response is more like the M. Who knows. Regardless, they're closer to traditional J-bass tone than the Bardens, and I think they're excellent.