Try Poston. My catalog is a little old, but it was $75, for the neck, the hose, and clamps. Then you get someone to weld it on for you, at a price to be negotiated. If you pay in beer, don't pay until AFTER the welding is done.
Also, if you put a wanted ad in the parts forum, Im SURE you'll find someone with a dutt neck IC for sale. Doing the job from scratch is alot more work than its worth. The turbo inlet may not line up when its done. You may have big lumps of weld and slag in the IC. By buying a used one, you can be sure that whatever crud was left over from welding, already got sucked up through the other guy's motor. Plus, you know everything will line up. Plus you'll have no down time, and you wont have to sit there and tell the welder a 1 hour long explanation of what he needs to do to get it just right.