Heislers are indeed a newer design–they started making them in 1892 and wer built until the Forties. A Climax might be a good choice for an earlier geared locomotive–the early Class A Climax models are quite aesthetically pleasing with their semi-enclosed cab and marine-style cylinders.
A link to the MDC/Roundhouse Climax:
http://www.mdcroundhouse.com/locomoto/Climax.html
