Larry there seems to be no change in the CGW situation since the last time you posted this question. I have found that the April 1967 RMC had an article on prototype CGW passenger cars but my subscription to RMC started just after that date and I do not have that issue. The Stephans Directory listing seems to suggest that one of the CGW cars was a former Milwaukee Road Hiawatha Car.
Dave Nelson
Larry,
Do a magazine search on MR's website... there was a Prototype Modeler Magazine - now defunct and out-of-publication - back in the late '80s on CGW passenger trains. The poster above is right - one coach was former MILW from the earlier '30's-era Hiawatha, bought second-hand by the Great Western.
Also, Carsten's book on the CGW by Phil Hastings has a shot or two on CGW passenger trains, and MR recently did a Pike-sized Passenger Train article on the Mill Cities Limited during the steam era. Other than that, it's hard to find material on this oft-neglected road. Anyway, you're going to likely have to paint and/or decal your way to a CGW passenger roster as little to none has been offered RTR. Considering how soon CGW pax trains were discontinued - 1965 - it's not surprising.
Good luck.