To mark the 70th birthday (and rumored retirement) of Luciano Pavarotti, “Unnatural Acts of Opera” presents a performance from the tenor’s pre-superstar period. It’s La boheme opposite Mirella Freni, with Thomas Schippers conducting, as broadcast on RAI (Rome) on July 17, 1969. After the acts, it’s even more of the Pav, singing scenes from I lombardi, Lucia di Lammermoor, I puritani and Rigoletto, 1966 – 1972. Act 1 begins tonight on Unnatural Acts of Opera.