In my honest and often wrong opinion, put them where you like, doesn't matter if it's original or not. The zed is great cause you can do all sorts of modification to it, airdam, flares, rear spoiler, wheels, etc etc and as long as it's tasteful, the community embrases it. All sorts of personalisations are in scope, and that's a very good thing.
I attempted to fit the fender mirrors as per the diagram and I didn't like where it placed them. It doesn't mean the diagram was wrong, I just didn't like the original, just as I don't like the original front end without an airdam. So I put them somewhere else.
Put them where you like, the s30 looks amazing, has aged incredibly well, but it isn't perfect so do as you please to make it your own.