Exhaust manifold question

Well here is the story. Went back to NY today and was visiting with the inlaws when I decided it was time to go down and get a few of the parts that he still had from the Dart Sport. I got the original intake manifold with the original TQ still bolted to it...while down there I noticed what i thought was a set of the original exhaust manifolds..turned out that the Passenger side one was cracked in half but the drivers side one seems(have not sandblasted it yet but no apparent cracks or damaged bolt holes) to be fully intact.

So question is on a 340 Dart Sport with power steering and brakes what do I need for the PASSENGER side as far as manifolds go..I was always under the impression that the one that really mattered fitment wise was the DRIVER side one becuase of clerance issuse and where it dumps? is this true...I was even under the impression I MAY be able to use a later model 318/360 PASSENGER side manifold? is this true...???? So basicaly what im trying to do is instead of paying for an entire set of exhaust manifolds...why not use what I actually have in the drivers side and see if I cant get a passenger side one for cheap or cheaper than a whole set would cost. let me know what you guys think.