In general, there is little demand for early 20th century equipment. Manufacturers have offered models from this era in the past, but there are only a few of these models that remain available. I understand the reluctance to chop up new models, but the only way to get most of the esoteric pieces you want is to kitbash or scratchbuilt them. And it is easier to start with an existing model than start from scratch. So the FNS kits are the best starting point to kitbash the New Haven cars from the 1920s and 1930s.