Try cprparts.com they make custom headers, but I have not used them yet. They are working on 1 7/8 headers for my 351W w/AOD but I was told they are one month out on them becoming sellable.
also check accufab or RCI. The price for the accufab/Klass header was 500 uncoated plus options but no AOD applications. Havent checked RCI but cost was over 700 for the fox5.0 header 10 years ago.
JBA has just released 1-3/4" stainless steel long tubes for the 64-1/2 - 66 Mustang with 289/302. They are not yet posted on their site but here is the run-down.
JBA is a rip off. I can't belive a company just upa and doubles their price for everything they make!! I couldn't find anything either. I had to go heddman 15/8.