Jerome,
I have this stem. It is unbranded but looks decent quality, in good condition and is a 90mm alloy quilll like you requested. The bar clamp measures just over 25 with my ruler, so I believe it is 25.4mm (can't find my vernier at the moment). More photos attached in a zip file. I would like £10 plus postage as it is like new.
I also have a Cinelli, Atax and Mavic quill stems in other lengths.
Hope this is of interest. PM me if it is any good