That part on the W. site that you linked to actually has slightly narrower string spacing than the true vintage bridge - 2.125" instead of 2.25" . So no problem there.
In any case, Warmoth sells only one Strat-style neck heel dimension, and unless you get a superwide neck with the overhangs at the heel end, you don't have a real choice. The question is this, I guess: Is 1/16" (per fretboard edge) going to make any difference in your playing? How wide is your vibrato bend? I would see if I could find a similarly equipped guitar in your local shops, and try it out. Bring a tape measure so you can actually see whether you're test-driving what you think you're after.
If you're considering a vintage-style hardtail bridge, I encourage you to check out the Hipshot parts - I really, really like this one that I have installed on my green Telecaster. If you need a black one, though, sorry - it's only available in stainless steel.
http://store.hipshotproducts.com/cart.php?m=product_detail&p=329