Treblig on this forum is an exhaust manifold guru. He would probably have what you need. Here is a link to a thread that shows some of his work and what he does.
http://www.forabodiesonly.com/mopar/showthread.php?t=304905
I have communicated with him via PM and he seems like a really nice guy! He has a very nice 69 Fastback Barracuda, so he is a Mopar guy and I'm sure could help you out!
