On the streamlined side, a PS set in aluminum would probably make more sense as the tooling is substantially cheaper. The 1950's PS coaches and 10-6s are pretty easy to do compared to a heavyweight car with specific window and rivet patterns.
Since no manufacturer makes the streamlined C&O Pullman-Standard cars in a scale length, I've put together a reasonable consist of actual lightweight and heavyweight cars to make a representative C&O train.
This is a stock Atlas RPO:
Modified a Lionel baggage car changed into a standard C&O Express car. I had Union Station Products cut the modernized doors for me. I have three of these as they were very common on most C&O passenger trains.
American Lightweight Car Co. combine kit. The C&O only had one of these and sold it in the mid 50's.
American Lightweight Car Co. 52 seat coach with Union Station Products car sides. The USP car sides have very detailed skirting.
GGD diner representing a standard C&O diner of the 1950's. Closed in the window on the far left making this side of the car fairly accurate.
American Lightweight Car Co. 10-6 sleeper kit. Used the ALW car sides so no skirting between the trucks.
American Lightweight Car Co. 11 Double Bedroom sleeper kit.
ALW kit with USP car sides making a 5 Double Bedroom/Buffet/Lounge Observation car. These were converted to Diner/Dormitory cars in the early 60's and the old heavyweight diners retired.
The kits take a long time and a lot of patience to build. I have another 11 DBR kit that has progressed to being primed. Have to wait until the weather warms up for the final paint job.
The most common lightweight cars on the C&O were the coaches and 10-6 sleepers and my consist needs another of each. I have one of the 10-6 sleepers from the GGD B&O Capitol Limited set on order that I'm going to repaint to C&O. I'll probably order a coach from the Prospector set to repaint once that set gets closer to production.
Ken