I think if you look at some header sites and check out what they call "block huggers" you will be able to make some work.
these style headers are short and tight to the engine block so you can tuck them in many applications that do not have any specific headers made to fit.
I think also that if you look and read all the posts on this message board someone was talking about how they did just that. the frame and body structure is nearly the same for all 68 thru 71 birds and they all had the 429 engine.