Rob,
The best resource for the vertical Climax engine is "The Climax Locomotive" by Thompson, Dunn & Hauff.
There are photos of the locomotive interior of S/N 313 which is a 12 ton with a 2-6.5" x 7" engine and a T boiler. This thing was a true rail yacht with the engine in the center and bench seats on the sides. The photo looks just like it could have been taken inside a boat in a marina parking lot.
There are also 3/4" scale drawing of the engine and gear box which is a simply another lever to change from slow to even slower. The drawing of the whole locomotive is 1/4" scale. Detail shots show all the main features of this rare Class A Climax survivor.
Dan