@Cold Desert Rat
Just so you know, I looked in multiple languages. I found several lists assembled by unknown sources, including the original Italian paint providers of Moto Guzzi.
In almost every case, they do not give a usable paint reference, but a reference of their own product, and like you found out yourself, there is very little about the V11 and nothing about the Copa Italia.
I was told that a spectrograph can pin point the exact color you are looking for. But you need to have an original sample.
If someone here has a Copa Italia, he can go to a paint shop and ask them to get the color code. Some paint makers sell "color readers", but the code you are getting is always translated into their own products.
Ideally, one of those HTML hexadecimal color code would work for you to get that paint from any manufacturer.
The best approach would be to get in touch with someone at Moto Guzzi. Someone who can consult the files and give you a reference.
Here's a link to a Moto Guzzi contact form;
https://www.motoguzzi.com/it_IT/contact-form/