Not sure you'd feel a massive difference between the two in terms of power, there are a few threads about it though.
Getting more than 330hp in any normally aspirated 350z is very difficult and will cost you a fortune, so much so that is would probably work out cheaper to go forced induction ie Supercharger or Turbo and have ~400 hp
Do not get a 350z if you want to chase HP. IT WILL COST YOU LOTS !!