Phat Cats have two A2 magnets, very dark in the neck slot, almost no treble. Sounds like it's in a closet.I swap mags and put in an A5/A5 or an A5/A4. That gives much more clarity and definition. I have a Dot with with a Phat Cat in the neck (A5/A4) it has more of an open sound than an HB would. The GFS Mean 90 (not 'Dream 90') is one of the best for the money (two A5's). Look under P-90's on eBay for more brands.
Any PAF in the bridge slot is a good choice and would pair up nicely with a neck P-90. It's a great pairning of PU's. I like a neck P-90 more than a split neck HB, which is pretty thin-sounding. You could split the bridge HB, and in the middle toggle position, it'd pair up with the P-90. And...if you put a second push-pull on the bridge for out-of-phase, it would also change which coil is on when the HB is split. That'd give about 10 PU combinations, instead of the usual 3.