Matt,
The B&O is pretty well documented.
I’d recommend “B&O Power” by Sagle and Stauffer which has been reprinted several times and should appear on second hand book lists.
If you can get to Baltimore, the B&O Museum is always worth a visit.
The Museum published a book “Scale Modelling and the B&O” by William Thornette. This is a big format spiral bound book (Metric A3 size pages) and it ha a lot of information about the B&O in your period of interest, including a set of drawings with photos of several locomotives, freight and passenger cars from the Steam to Diesel transition period, the drawings having been published by the B&O in the the 1940s and 1950s for modellers.
I picked up a copy on my last visit to Baltimore in 2013. It cost $9-00 (!) over the counter at the museum and it must be good value at that price for 75 pages.
For your period, the B&O operated USRA light and heavy 4-6-2s and light 2-8-2s (B&O 4501, a light 2-8-2 and the first USRA loco built is in the museum). The B&O class P-1 4-6-2 and Q-4 2-8-2 are included in the drawing set, and these show how similar to the USRA standards ordinary B&O locomotives were.
The Pikesville line is now used by MARC for commuter service, so I assume the B&O probably operated similar services in the 1940s.
But generally you should have no trouble finding data on the locomotives and cars from your era of interest, and many models already available. Rivarossi used to make a model of the B&O 2-10-2 and again, one might be available used.
Peter