440 big block conversion for a body

Are you only interested in selling this as a whole kit? I have been trying to chase down similar exhaust manifolds. There appears to be a lot of controversy about whether or not these will work in my 440 '67 Valiant. How did they work for you? Was there any difficulties or problems/mods you needed to do to get the exhaust to fit? Seems much cheaper way to go than swap headers.