ITR41,
I may sound like a RevHard salesman, but go with one of their kits, the components are first class and track proven. If you think you can come up with the right turbo combination for your car on your own, good luck!
If anything, at least call Turbonetics to set you up with a turbo that is efficient in the range that you want to operate in. Unfortunately, they do not sell direct. I've been down the road you're trying to travel, and did some very in depth research on piecing together everything I needed to turbocharge my ITR, there is no money to be saved building your own kit.
Lisa Kubo and Jotech + countless others use RevHard kits on their cars.
I would be more than happy to give you more info on my own turbo install, if you need it.