Personally, I would not consider putting a non-Porsche motor in my car. But that's just how I feel about MY car. I would love to see someone build a 600-800 HP Boxster. If in achieving that end, that person elects to use a Toyota, Mitsubishi, or hovercraft engine in their car, it just makes the project more interesting.
I really hope you do this, and I hope you keep us posted along the way.