I did search through Google quite a bit with little to no results; otherwise I wouldn't have come here for help. However, I did not see the Historical Society's magazines. They do have one comprehensive article on hoppers, although it's strictly numbers and dates as opposed to a pictorial guide. An interesting quote on the shortage of B&O hopper information:
"Surprisingly for the third largest hopper fleet of all U.S. railroads (behind only the Pennsylvania and the Chesapeake & Ohio railroads), only one published article in the enthusiast press to date attempted to systematically address the B&O’s hopper fleet
(“B&O Hoppers: Prototype and Modeling”, Barry Rubin, The Sentinel, Fourth Quarter 2003.) Many other articles addressed modeling individual car classes, but the B&O modeler (as well as modelers of other Northeastern railroads) lacked a comprehensive
resource on building a representative fleet for his or her model railroad."
http://borhs.org/ModelerMag/BO...r_2_2006_MayJune.pdf
I first searched the years the K-Line road number would have been in use and found that they were retired in 1934, well before the EM-1s were ordered. It also did not say those road numbers had peaked ends, so they're definitely out.
Will continue looking through the numbers.