Lon, the 1916 ICC Structures Valuation Report describes the construction of the ph. booths in detail, as well as the general location, such as "McCoy" or "Larch". At one time, we did have reprints of the report for sale in the gift shop. You might contact Taylor as I know there has been talk of doing it again. There are detailed drawings in existance of the SVRy ROW with the locations shown for each structure, not to mention small details such as derails on sidings and the like. One such set of maps is at Eastern Ore. University in their archives. Some of these maps were updated over the life of the railway. Bob Berstrom who is SVRR Archivist and myself have discussed the possibilty of getting these maps copied. If we do so at some point, I presume copies would be made available from our own archives for a fee.
There is actually quite a bit of SVRy data in terms of original company documents still existing, but it is spread around quite a bit in many hands.