Re: Sumpter Valley Ry. Trucks

I note, as per the attached screenshot from the National Archives online catalog, two Forest Service timber sale files for Oregon Lumber. Outside the range of the screenshot, two other files noted, one for Stoddard, the other for Cavanaugh.
Timber sale files can vary in usefulness, but if they contain an appraisal, that document alone could be worth the 80 cents per page (last time I checked) for a copy of the file -- you have to order the entire file.
Another useful document, if you can find it, is the timber management plan. Did not see any indicated for Wallowa-Whitman; perhaps, though not likely, the Forest may have a copy for the period of interest.
It may be worth your time to look at the online catalog yourself. I used the advanced search, keyword "Whitman," record group 95.

JH