I'm not sure about the C&A. I'm guessing that you posted part numbers rather than product numbers. I'm 90% sure that the 6-11334 Southern had smaller driving wheels than the 6-11335 Blue Comet that was released at the same time. So at least some of the scale Pacifics have parts/frames that are not interchangeable. I think the C&A had large driving wheels like the Blue Comet, so for my $.02 the Southern frame won't work.
Also: I can't remember whether the frame castings were painted to match the boiler shells. I certainly wouldn't want to pull and press all of the driving wheels, but if the frame is red, it might be hard to repaint it otherwise.
