For the life of me i couldn't understand what in the heck you were asking with your 12 volts into turbo question. then it dawned on me. I am not smart sometimes.
No joke the fordcummins kits are expensive.
450 to the rear wheel?
What's your budget? What do you plan on doing with said vehicle setup ?
I have an 01 with nothing more than an S300 turbo "BD super special" which i absolutely love, quick spool and holds up to 45 PSI
with no issues. But being a 24V I am running a tuner (quadzilla adrenaline iQuad)
A few things i would recommend for your 12V project.
1. 3Pc manifold (you have to use a 3rd gen mani don't you?) helps spool time and prevents cracks
2. RV275 or roughly 75/100 HP sticks
3. S300 turbo or start looking towards the HE351 VGT turbo and controller
4. Fuel plate (your choice)
5. FASS system to fuel that poor thing,
It would be drive-able yet TONS of power when you need it.
Posting on Dieselbombers might net you better results for cummins questions