VTEC just broadens the torque curve. It's nothing special.

Revving a stock z6 to 8500+ rpm is a great way to install a window in the block. Make sure you don't snap the throttle closed. Running a stock z6 making 420 horsepower is a great way to lower the compression in one or more of your cylinders.

I don't even understand the desire to rev the engine that high. If you can make the same horsepower at lower speeds, it'll be much more reliable.

Also, I'm running a b7 block because it's my daily driver. I don't need anything fancy.