There were two styles of Austria-tooled covered gons 40 years ago. Lee's model is the gon based on the PRR (PC) prototype, but I think the BM car was the other style.
Regarding the AHM-released Flexi Flo hoppers - those are based on the ACF pd3500 hopper manufactured solely for the NYC in 1964. They had extreme longevity, lasting as a fleet until very recently, and there still are a handful active in private company service I believe. But yes, they generally ran between Chicago, Boston and New York on the old Water Level Route because they could only be loaded/unloaded at specific facilities. The biggest facility was in Saugerties NY, and most of the cars were stored/serviced there when not generating revenue.
All of the road names offered by AHM on both models were not prototypical.