The earlier ones tend to have those holes on the seatstay caps rather than the "Grandis" engraving. Here's a circa '77 that just sold on ebay with the "Grandis" version:

http://tinyurl.com/lqr7nz

Bikes from just about any of the better Italian builders are rare to see in the US from that time period, IMO. Especially the smaller, lesser known marques that AFAIK wouldn't have come into Velo Sport or Cupertino or Kopps or one of the other cutting-edge shops bringing in Italian bikes. A really nice, unusual acquisition. I believe I have some lavender/yellow striped ribbon tape I would be happy to send you for free if you are interested and send me a PM. (My Picchio Special is also purple but a bit darker shade, interistingly.)