Here's a list of sources for exhaust pipe bends, and also some sources for aluminum for air inlet plumbing.
I just added the above link, they have some good stuff.
http://www.4btswaps.com/forum/showthread.php?t=6362

Grigg


•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-