Looking to buy/build 500-600 fwhp 360

Update, I have purchased a set of Icon flat top forged pistons. The original pistons had a zero deck quench area but were slightly dished. I did not want to mill the heads 060 to get 10.1 compression. Now i'm on the other end of where I want to be. The compression ratio will be about 10.9. I can mix a little race gas (ugh). I don't know if putting a little thicker head gasket will get me to 10.5 How about porting a little more to get both better flow, and increase chamber volume? The other thing I thought about is using the box I am going to install to retard timing while on nitrous and use it to retard timing when I am running pump gas. Or, can I get away with 10.9 at 3200 feet on 91 octane? I need an anti knock sensor...