Wow, this thread is going nowhere on answering my question. It went from having to describe I have a magnum, to saying I have to get a custom cam otherwise nothing will work (hogwash), to 110 will not work with exhaust manifolds so I should get a less efficient 114 cam (hogwash), and to now defying my builder by throwing his "catalog" in the trash, which would mean the end of my 408 build.
Thanks rumblefish360 for one of the only helpful responses. The problem will calling converter companies is of course my factory converter will not work, because I need to get theirs!
I'll try to ask my question (that I've posted at least 3 times so far) somewhere else because this is going into a ditch.