Recently I made a rather spontaneous purchase of an EMG KH20 , basically a prewired pick guard with S/S/81 pickups. I'm now looking to build a guitar around it, my current favorites are a Stewmac strat style swamp ash body and a Warmoth Pro neck (either strat or jackson style, haven't decided yet), maple with a rosewood fret board.

What does everyone think of that combination?

Is swamp ash okay for this type of setup, or should I be looking at a different kind of wood for the body (mahogany?)?

And, is there any reason why I should go for anything other than the standard maple for the neck?
I think that you might want a mahogany body for it instead of swamp ash. I've never personally tried an alder guitar with EMG's but I think that swamp ash is supposed to be brighter than alder and most people say that paired EMG's alder has too much highs so you might want to rethink that. I don't see why you would want anything other than a maple neck, I mean its widey used for a reason.
Stock Gibson Pickups from a 2005 V, I think they're a 498T and 500T set FS/FT
Duncan Distortion (regular spaced) FS

Looking for: an acoustic, recording gear, or $