I ran into the same issues with my Dart. I wound up building my own headers. I work at a dealer and scoped out or tried on every possible factory manifold.....no way.
So I cut the flanges off of a $100 set of headers I had and ordered a 1 3/4 header kit from Summit ($120) along with some V-bands and went to work. This was the first set of headers I have ever done. It took me about two weeks on and off to do them. The turned out pretty good (I think). There is simply no room on the drivers side for any other option. Take a look at my photobucket album. Take your time and plan ahead.

Dave
http://s1083.photobucket.com/user/swinger440/slideshow/