Okay, Roger...here's my choices...
PHOTO 1 - shows the big black stack plume that folks associate with steam egines...clear shot of the engines without too much BG to distract.
PHOTO 3 - gives a sense of the Old West which I think was being conveyed in the pamphlets.
PHOTO 7 - Everyone loves a tunnel...kids gotta have a tunnel on their train sets. This photo sets off the engine nicely.
So I voted for three...choose the two from there yourself...I can't I like these three most...but I like all seven!