If you are gonna race it for extended sessions port the entire blower and snout, and go with a 2.85 upper. It will make similar power to a 2.5 or 2.4 non ported blower, and IATs will be lower.
You'll get 550 WHP easily with good exhaust, headers, intake, a tune, a port and a pulley.
If you really want to make sure you get there throw in an LS9 cam, they are $100 bucks and worth 30 WHP or so over the stock LSA cam.