An altezza isn't really an option is it? Ya can't import them and get compliance here in aus :s
I'd go for the IS300... I've not heard one good thing about the 2lt six in the IS200...
As for wheels, the car is more of a cruiser than a sports car, multi spoke wheels in a dark hue would compliment it's styling much like the stock wheels on an IS-F.
My choice would be SSR Type-F in flat black

or maybe Type-C if ya had bigger brakes to show off

you can check them out at
http://www.ssr-wheels.com/wheels/ssr.asp