Re: Neck Humbucker Single Coil Help!?!
Mincer's suggestion of using a Fender-type single with a mounting adapter is the way to go for an actual Strat pickup. Good idea, and one that wouldn't have occurred to me immediately.
I love P90 neck tone myself; if it were my guitar I might well go with the lowest wind humbucker-sized P90 I could find. Phat Cat neck would be the Duncan one.
Barring that, the StagMag would be the obvious choice, for true single it could be wired permanently split, but if you have a couple of controls one could be a push-pull: might as well have full series available for once-in-a-while hot neck lead tone.
DiMarzio claims the Humbucker From Hell sounds like a singlecoil. Actual users seem to feel it is a good bright humbucker for neck position but might not be as close to singlecoil tone as claimed. I wonder how it would do in parallel?
Another option is a bright low output humbucker. Some of the PAF clones can approach single coil tone pretty closely, perhaps not quite as plucky but they have genuine chime. Haven't owned a Duncan Antiquity set yet- they may be more towards the warm end of the PAF spectrum. Gibson's BurstBucker 1 is bright, and some swap them out in favor of higher output pickups so you can sometimes find 'em used. Swapping out the A2 mag for an A5 would make one even brighter, and mid scooped too, which could bring it a couple of steps closer to Fender tone. Some of the boutique PAF types are quite chimey & articulate though they can also be quite pricey. If cost were no object I'd recommend the Tom Holmes 450/A4 or PRS 57/08 neck pickups, two of my very favorites and both are absolutely stellar. Also winders like Zhangbucker or ReWind who will make a pickup custom tailored to your taste & needs. Or the Duncan Custom Shop where MJ will do the same, with all her years of experience and a satisfaction guarantee. But again, any of those options run to more time & money.
Going in a less expensive direction, I have a cheap overwound humbucker from Dragonfire (Phat Screamer, 17K/ceramic) that I've been thinking about using permanently split in neck position. I just have so many better humbuckers sitting around that I keep changing my mind about it, telling myself I should go for something with noise rejection.
But like I said, if it were me I'd probably go with a humbucker-sized P90. Maybe not particularly Stratlike, but it is a singlecoil after all.