Hey,
I would recommend two for the middle coil, I don't know what you exactly looking for,
But, I like low output pickups, drives the amp differently. Dimarzio's Area 67, output is around 5,6 or something, its got very strong high freqs.
Another thing, if you like the quack sound on the 2,4 position, Id go with the duncan stacks.
About the BKP, one of my favorites ,considering BKP single coils, is Slow hands.
But I thing the Sultans coils are the ones with the quack sound.