Trevor,
I only have "Railways of South America, Part II" by W. Rodney Long, which covers Bolivia, Columbia, Ecuador, Guianas, Paraguay, Peru, Uruguay and Venezuela. It was published by the Department of Commerce, Trade promotion series no 39.
According to the Letter of Submittal, rather like a forward, this was the fourth of a series on railways in Latin America. The first was "Railways of Central America and the West Indies". The second was "Railways of Mexico", the third was "Railways of South America, Part 1" which covers Argentina. The fifth and last volume, "Railways of South America, Part 3" covers Brazil and Chile.
Lots of financial data, but maps and equipment lists of the type found in the offical guide are included as well.
Michael Allen