There is a Reno Builder, Della Santa, who built Frames for Greg Lemond. This one looks like maybe it is one of his.
I had owned a Billato built bike and sold it to a friend. I currently have a Scapin built GL (1990) and imported through TenSpeed Imports. Most of the European frames were brought into the US through TenSpeed. I couldn't see the decal (it is white with dark lettering and a S/N). Google Della Santa and send him the S/N from your bike.
The SL looks like it might be from the 86 time frame. They are great bikes. Although I have a collection of bikes the GL is still ridden a lot. I was luck to have gone on a ride where GL was doing a promotional for a bike store. I got him to Autograph the left chain stay and put some Clear chainstay tape on the signature.
I did upgrade the bike with a 1991 Campy 8 Spd chorus group. Still rides like a dream.