I had the same thought with reagrds to a broad torque curve.
Here is my approach in progress:
2.5 built block (pistons and bearings)
V8 big port heads w/ Helix valvetrain, oversize valves and V8 cams
GT30R .63 turbo
Ethanol injection of some sort
We'll see what happens. Should be up and running by the end of May beginning of June.