81-83 sounds right to me, but I could buy 1984. I'm no DeRosa expert, but several people I trained with had these during this time, and I remember them. DeRosa was ahead of the trends on both under BB cable routing and front derailleur mounting. The first braze on front derailleur I ever saw was on a friend's DeRosa circa 1982.

Edit: Actually - the first braze on FD I saw was on a Rigi, circa 1980, but those are a special case.