If going down the P90 route, consider the ( Alnico III ) Manhattan. Much more 'air' and more subtle dynamics than the Mississippi Queens ( as good as the M.Qs undoubtably are ) . The Manhattan has a very rich tone, which you may / may not not wish for your current needs ; but I mention it ( in your situation ) -as it has the Alnico III magnet, which is much used in the sweeter / detailed Tele and Strat pickups.
I have also been experimenting with a VHII ( Bridge) in a 'Superstrat' type guitar recently - and if you get a pot/ switch to coil split it, the classic single coil tone is surprisingly well represented - whilst a very clear and relatively 'single coil-ish' tone is also found when operating it as a Humbucker - but in the later case with more power of course.
If in doubt, of course ask the chaps at B.K.P. :)
(* Edit *)
Upon reflection the VHII split , will probably cut through the solid slab Mahogany of the S.G better than the Manhattan.
If you do go down the path of a B.K.P Humbucker being 4 conductor wiring / Coil split, it would also be very worthwhile trying the pickup mounted in different directions ( i.e screw coils closest to neck / screw coils closest to bridge ) - to effectively put the resulting single coil about 1cm further up or down the guitar .