You wanna make 500 hp out of a NA engine not bigger then 3 liters? That means you need a high reving engine. (take the NSX engines for example). A high CR (11.5:1) and therefore high octane fuel. I think you need an adjustable length intake.
And you are gonna use it as a daily drive? Then I assume you want some low end torque also?
In my opinion (but that is only from my point of view) 500 hp is a bit to high for an 3 litre NA engine in combination with a 'daily' drive. (but I don't say it isn't possible, it can be done with the right amount of money. And as you talk about OS giken that doesn't seem to much of a problem) I have my doubts by the low end torque (I don't think you wanna rev the engine to 4500 revs/min everytime you pull away from the traffic light.) in combination with high power.
This is not ment to discourage you.
Derby
(I hereby apologise for my reaction if I understood something wrong)