Herb McCandless told me that the later Hooker super comp A body headers will work (#5215-1&7/8). At one time decades ago I mocked it up & the dr side fit but 2 tubes on the pass side needed to be cut/altered. Speedway mtrs has leftover pieces from header building for cheap or call your local ex shop (get the same gauge). Reportedly tire rub is the issue & 14's or low profile 15's are likely needed. An option I am considering is max wedge iron manifolds but they are pricey (but the headers are too) & I'm sure the manis would fit with a B & the 68-70 HP iron manis would for sure would fit & I saw a pic of a '66 A with a 440 (RB) with the max wedge manis & they fit. build tolerances in early A's were the worst ever but they are my fav & in some cases the 68-70 HP manis will even fit with a RB (steering col housing is the issue there) but you can shorten the housing (mock up & go from there). You'll likely need to remove the pinch weld in the sloping trans tunnell and in some case raise the tunnell (the tolerance thing again) & I have a JW ultrabell to adapt a 904 to a big block which will guarantee a no weld tunnell fit. Just need to find another good A body roller to work with & they seem to be gold plated these days. EDIT I have streetmaster spool swap mts (nice pieces) but not sure if they are even still in business