Hi Terry -
That Mexican Strat is going to be alder, right?
FWIW, I'd try an APS neck, SSL middle and either a Twangbanger or a tapped Quarter Pound in the bridge.
Unless you're going for the Antiquities or Fralins - haven't tried either and want both.
The Alnico 2 APS in the neck is nice & smooth. Having an SSL with alnico 5 in the middle brightens up position 4 (neck & middle) and gives you more sparkle in the middle position. It can produce an almost acoustic sound if you run your amp really clean. For the bridge, I'm just not that big a fan of vintage Strat pups - I like a stronger, fatter sound and/or some tele twang. The TB is an obvious choice, but I put a steel plate under a tapped QP while everyone was raving about the TB but you couldn't buy one yet and really like it a lot. The middle/bridge position sounds like a strat, but the bridge by itself is more useful (just IMHO). If you wire it so you can get neck & bridge pups together, that adds a really nice Tele-type tone to the Strat's arsenal.
BTW your neck radius has a lot to do with whether or not you should go for flat or staggered single coils. With a 9-1/2" or smaller radius, the staggered coils are probably better. If you've got a 12" or greater radius, you really need flat poles. In between, it's your choice. The MIM Strat is 9-1/2" unless my memory is bad...
Hope this helps,
Chip