The Piaggio decal and 600EX would normally indicate a circa 1981-1983, Japanese, mid-range model, typically a Limited. Yet, a top tube decal with Super could be a partial Super Leggera, which was a high end frame. However, the decals do not look look familiar and I would not have expected vertical dropouts for this era. Still, Bianchi could vary substantially, depending on the intended market. The bottom line is we need more info, specifically the info on the tubing decal and the serial number. The serial number may be in one or two parts, either on the bottom bracket or possibly both sides of the seat lug. Pics of the tubing decal would also be appreciated.