To the best of my knowledge, combined with a quick browse through "The Willamette Locomotive" by Steve Hauf and Jim Gertz, I don't believe any of the 33 Willamette's were narrow gauge.
As to the Willamette logo. That starts appearing in the photos in the book starting with construction number 19.
The "Geared Steam Locomotive Works" web page
[www.trainweb.org] has more information and some photos of Willamettes.