Bill,
Looking at what you have there in terms of intak and exh... I dont think that header's going to help you with the exception of mounting the turbo Heat is key, as you said, and the length of that thing (and shape) will just pull heat out and slow down the air as it moves closer to the turbo. Not to mention the elasticity and compressability of a gas. You may find the turbo extremly lazy as a result. In regard to the cam... I don't believe basing your decisions on the V6 configuration guys is a good idea simply because their packaging is drastically different and much more efficient. Not to mention the tunable electronics running them. Powerful turbo cars make the most of the exh gasses, and pump the maximum amount of air as a result. An aquaintence's late 90s Mustang street racer has a 370-something" engine with a large single turbo. It idles like a stock mustang, yet runs in the 8s. It's all about the manifolding, turbo sizing, and tuning. Much more so than the cam.