What state are you in? I know that in Qld, a car can't have an engine with a displacement greater than 3 times the cars weight, with a turbo or supercharger.
I was contemplating a 5l V8 with a decent turbo but the rules up here wot allow it.
Biggest I could go was a 4.5L then add a turbo - which is still tempting.
One of the guys up here put an ls1 in a 33 and then realised, far too late that he can't boost it. Just a bit of a heads up mate.