Basic design questions for a 6.0 turbo build

I know that all these questions have obvious answers (go big or stay home), but please consider the cost vs benefit in making your suggestions.
1. Stock crank or aftermarket 4.00"? Is a boosted 408 going to be more street friendly than a boosted 370 at similiar power levels? I am thinking about spool time, low end torque, off boost performance. Since I am going to buy new rods/pistons it would only be the cost of a new crank.
2. Truck manifolds or tube headers? Can the truck manifolds support the power level I am shooting for (roughly 800 rwhp)? Is it easier to package with one or the other? The LS turbo headers from Stainless Works look like a budget alternative if they work in a Nova...
3. Single vs twins? I am currently planning on a single turbo. With a 9:1 ratio 370 or 408 and a single (T76 - T88 depending on engine size), will it have decent low rpm manners? Is there enough benefit from quick spool twins to justify the added expense?
4. What style intercooler? Is an air/air adequate for my goals? Where is the point that an air/air IC should be upgraded to air/water? Is an air/water system street friendly? I do not want to replace my passenger seat with a heat exchanger.
I'm in the process of picking up a used 6.0 engine now, and I'll build it before tackling the turbo side. By the way, does anyone want to buy a Dart SBC block? I am abandoning the big inch SBC build since I just can't shake the LS bug.
2. Truck manafolds guys here are running in the 7's, over 1k hp and then some so you really dont have to use headers but with the truck manifolds you will losse stuff like a/c and relocating your alternator.
3. I would stick with a single turbo due to the cost factor of 2 turbos ,2 wastegates and so on. you will have good low rpm manners.
4. air/air is good for what your looking for. as far as when should you upgrade to a air/water hummm, that is a very wide question and you will get a lot of different answers.
ps. I would do like 8.5:1 compression. Also i would look at different guys combos on here and what type of times they are running like i did. Look for proven combos. Good luck
1) Stock Crank 370
2) Truck Manifolds
3) Properly Sized Single
4) A2A


Old set up with a single. There is not much room under the hood.
http://www.cardomain.com/ride/2251820
Some pics of ther intercooler for a single.








