They are not being reproduced as far as I know so used is the only current source. The C body drivers side is similar to to the A body manifold (they look identical in design when looking down from the top) and would probably be a better choice as it does not have the restrictive downpipe jog that the A body has. I have put one on a head in my 383 Dart and it will take a little creative work making a pipe to clear the steering column but it should work, my car is manual steering so I can't say how it would be with a power steering box, though I know that the A body manifold also has an indent cast into the # 3 tube to clear power steering that the C body does not have.

I have a set that have been ported by one of the original FAST series racers , Greg Gessler RIP , the one thing he didn't do was take out that divot before the manifolds were jet hot coated, he did address some of the restriction at the output flange. As far as the right side goes a standard 68-69 B body should be fine , it just doesn't have the long down tube so your headpipes will have to be custom , which is pretty much the case anyways as I don't think anyone makes headpipes. I had the 2.5" headpipes I have made custom, they are mandrel bent, cost me about $900 for my hybrid system with TTi tailpipes back in 06 .

The Body is said to also work but I think the steering column tube needs to be cut back flush to the firewall?

If I have the chance I'll try to post pictures of them all tonight .