Clifford Intake and ? headers
Clifford did make a long tube set years ago, but it was a 6 into 1 header. Not a pair.
To the best of my knowledge, Clifford never made a 6 into 1 header for a slant six. At one time Clifford had more then 10 different slant six headers (depending on engine/vehicle), all long tube, two outlet. The Clifford "shorties" were made to reduce cost, two sets to cover all applications. Mopar Performance had a single outlet header, at one time. The headers in the pics, look similar to older Cliffords, but can't say for sure. The collectors don't look like the Cliffords I have seen, and the routing of the number 4 & 5 pipes are different. But I have not seen every configuration of Cliffords. They might also be Hookers, or even another company that I am not aware of.
PS: FYI Clifford headers did not have a "brand" or part number on the header, just a paper tag, like a store price tag, with the part number. All Clifford slant six headers were tagged 55-xxxx
PPS: also back in the old days, Jack Clifford would make "special" headers for serious class racers. He made me a few sets of different length & diameter headers, for my Z/SA 65 Valiant.