I have an HO brass shell (Railway Classics?) TCZ Observation Car that would be a much better starting point than the CZ car which has the raised rear roof, dome in the wrong place, and windows needing to be moved around. As I got it to serve as a model for making an N Scale version and Bill Denton and Mike Skibbe have made resin shells for the car I would consider selling it if anyone is interested.
The BLI cars can be used for non-CZ cars if the ownership plates are removed and the mounting area behind them reworked to extend the corrugations through them. The CZ baggage is good for the Olympus and Argo and the diner is really close to the TCZ and DZ cars. Have to do a study on the domes to see how the windows vary across the various cars and also look at the 16 sect vs. the flattop coaches, parlors. The BLI 10-6 is good for a couple of pool cars but the DZ 10-6 has different windows/floor plan.
Charlie Vlk