Still haven't found the picture I was thinking of but I did find another frame that has the same bottom bracket engraving. This one is an Esposito (Massimo & Salvatore, out of Milan). I'm not saying that your frame is an Esposito frame, only that the bottom bracket engraving matches. I've only seen a handful of Esposito frames online and they've all been heavily pantographed (with lots of stars), so I can only assume their work would be easily identifiable.
Cicli Esposito is still in business, so it's another avenue that could be explored. Perhaps they may have more info on this mysterious BSE lug manufacturer.





The rest of the picture set can be found here.