For track use, I'd suggest that a 1.06 turbine housing on the GT30 is a reasonable way to go, with more efficient turbine flow and reduced backpressure for better scavenging and reduced retained heat. And the 60-1 compressor while not ultimately as efficient still isn't a bad thing.
Arguably the best thing about using the GT35 turbo is that you've achieved more efficient turbine flow and would consider using less boost to achieve the power target but not smack into traction/driveability issues that Scott is alluding to. And if you're thinking of trying to use 500rwhp in a 2wd chassis and effectively get it to the ground on short/tight tracks then good luck.