The only suggestion regarding PSE Green I can come up with is to contact Warren Wing. He lives just south of Seattle in Allentown and has a huge collection of Pacific Northwest railroading photos. He has published at least three books from his photo collection that I'm aware of. He may have a website--- I don't know his phone number. But I would think if anyone has a photo or can describe the shade of green used by PSE, it would be Warren. He's getting up there in years but the last I heard he was living in the same house he was in when we interviewed him several years ago.
(to reply remove Boeing jet from address) ______________ C. Marin Faure Seattle, Washington