A decent set of pistons in an unmolested shortblock, a little massaging on the heads and the correct combination of bolt-ons (this is where you make the power) will get you 400rwhp with no problems. Regardless of what you do internally, you are still going to need the right combo of bolt-ons (turbo/exhaust/IC/engine mgt/fueling) so why go to all that trouble and expense unless it really makes a difference that you make 400rwhp at 7000+ instead of 6000. With a turbo engine, the higher you push the power band beyond stock, the less "rock solid" things tend to get. One thing that a lot of folks miss is that a turbo engine is all about torque and if this is a street-driven car, you go for torque as low as possible rather than hp as high as possible. What your combo is doing is lowering the torque and moving it up higher in the rev range.
OTOH, that is what makes the world go round. I love seeing people come up with new ideas and I hope it is the right choice.