Ive had one of these since 1977 and the way the color varies depending on light conditions has always struck me. In bright full sun, it looks gold, with almost no hint of green. But in lower light it takes on the lemon-lime sort of color you describe. I'll bet it's hard to match. The"Legnano" script on the downtube of mine seems to be stenciled or painted somehow, rather than a transfer. I would try to describe panel location, etc., but I'm sure there are good photos online. Contact me off group if you cant find anything.
Best Regards,
Wes Gadd