I think the injectors bring a margin of safety above 600 hp. If you might run E85 then consider this now as you will need much bigger injectors - that said without forging your rods atleast or fitting bigger turbos you will only be able to get so much power out of your set up.
What you suggest sounds good although if your not going mad for power then panel filter upgrades would do inplace of full inlets and if your doing the downpipes it should help remove some restriction at the top of the rev band anyway.
With the tune, what would you run? Cobb or Ecutek I assume?