JC Cosmo = Best block for forced induction applications.
Massive intake ports factory.
Slap on a S5 Turbo.
Aftermarket computer.
200kw + at the wheels and you won't be stressing the engine.
If you need any engine parts, hit up Fairview Motors on Te Rapa Straight, I got quite a few bits from there, my contact left but last time I went in a guy called Bevan? hooked me up with a pretty hefty discount (IIRC it was better than trade).