If they're for FE, it sure looks like shorty headers designed for use with a full size car (Galaxie) due to how straight the primaries flow out of the head. FE headers have to turn down hard right away to clear the shock towers in smaller engine bays like the Mustang, for example.
In specific, the pattern of the headers looks more like the 1965+ Galaxie shorty headers to me, though it's a bit tough to say from the photo angles. I think the 1964 and older have less vertical drop on the primaries on the passenger side, while the photos you supplied seem to better match the 65+ patterns which seem to show what looks like the header primaries dropping lower down the block.
Totally guesstimating, though. In any case, from my understanding, neither header pattern is interchangable. So 65+ will not fit 64 and earlier and 64 and earlier will not fit 65+.
