According to the Condorino site (I'd never heard of it before - thanks for expanding my horizons), Legnano started calling their top-end bike the "Olimpiade Record Specialissima" in 1970," so that's as early as this one could be. it also says they stopped using Universal 61 brakes in 1972. Add
juvela's dates re the 3ttt stem, and we are looking at it most likely being 1971 or 1972. The site also says the distinct Legnano seat post bolt set-up was "'fully' discontinued" as of 1075, which goes against the 1971-72 theory. But the wording suggests that it might have been phased out over several years, so my guess is this one is one of the "early adapters" to the new-fangled style.
In any event, it looks like a cool, high-end bike and I learned some new stuff. I call that a good day.