Surprisingly, I never considered running it in Savage Worlds. I'm not that into the system, unfortunately. I do recommend War of the Dead though, and just remove all the railroad it contains.
As for Microlite... honestly never heard of it. Where can I find out more about it?
Where are you finding the free pdfs? I've been wanting to get Deadlands for some time, just never got around to it.It's not zombie horror specifically, but it does the job great: Deadlands.
I prefer the old pre-d20 version, which you can get as free PDF's now.
You could also use Pelgrane's "Fear Itself," which adapts the GUMSHOE system for normal (not uber-competent) people. It does a fantastic job of simulating a great horror movie.