The $4k is not bad, it is the fact that the 80's are cheap now that skews the equation. But you save on the truck, spend on the performance.
As for turbo, I would take that every time over SC. For people considering the turbo manifold I would suggest that you talk to Landtank about what happens if that manifold cracks. I know he is not a business selling them, but you would then need a replacement. Even Safari that has a lot of experience with turbo's had cracking issues.
He is doing a great job designing that, and he did say that the company makes them for the BMW crowd, so one must hope that it will be the right metal composition to prevent cracking, but the problem still might come up. Not sure if he is going to stock replacement units.
Also, to put a kit together for $2500 is going to take some doing. The devil is in the details. $2500 might cover the big ticket items, but the plumbing and all the small items add up pretty quick.
Just as a FYI>