Pat
Anchor points on a Giulia should be found in the sill area as pictured. Attachment of a three point belt should be do-able by reinforcing an area on the wheelwell area above the softop securing straps.
http://wescoperformance.stores.yahoo.net/seatbelts.html sells different designs of belts at reasonable prices. They are not much help when it comes to "what fits my" or "how do you" questions.