I believe any 68-76 A body manifolds for a 340/360 will work. The drivers side has a very noticeable shape needed to clear the steering.
I used 72 340 manifolds on my 69 cuda with a 360, as they were much cheaper ($200) as opposed to the 68-70 which go for $5-600.
I believe that the drivers side exhaust head pipes are the same from 68-73. The passenger sides are different because the exhaust manifolds are different shapes.