plus it's nickel and the rest of the Am series hardware is chrome (you'd think they'd cotten on to this as the bridge is specifically for the Am Series?)
Yeah, I know what you mean, I don't like mixing nickel and chrome hardware on the same guitar either. :(
It's OK on vintage-style Strats because there's always been that mix, but anything with modern hardware I want all-chrome or all-nickel.
On the plus side, I'm sure the Callaham bridge will give you a much better vintage-style tone. My Fender bridge may be made of "vintage" materials (steel plate, brass saddles) but the thick baseplate stops it sounding very vintagey at all really.