I have been looking too and the answer is no. Though the exhaust kits from a 73-74 should work they just will not have the cats. I think when I get mine redone I am going to tell them I have a 73.
I took my Valiant to the local Midas muffler, brought my own
Dynomax Super Turbo mufflers, and they did a great job
of making duals off the stock manifolds.