Before he became the master of oratorios, Handel was a purveyor of the Italianate opera. He wrote dozens, many of them tailored to the peculiarly voluptuous voices of the celebrated castrati of his day. Tolomeo, a flop when Handel produced it himself in 1728, doesn’t quite belong in the company of Orlando and other masterpieces, but it ought to be thought of as more than a footnote to an illustrious career. Its story line, typical of the opera seria, is embellished history: Ptolemy, king of Egypt, is exiled by his wily mother and brothers to the land of Cyprus. There he falls madly in love with a local girl, but after much soul-searching and advice from sympathetic lieutenants he returns to Egypt triumphantly though regretfully. The characters’ emotional twists and turns are suggested by the floridly ornamental vocal passages–showy Handelian arias that are sure to be handled with grace by Drew Minter, the New York-based countertenor who’s the star of this Basically Bach concert presentation. (The use of castrati, incidentally, died out in the early 1800s.) Also in the excellent cast are soprano Carol Loverde, bass-baritone Andrew Schultze, and contralto Patricia Deckert. Conductor Daniel V. Robinson shows prudence in choosing an obscure Baroque work for revival by his diligent, mostly period-instrument band–a more worthy cause, in my opinion, than yet another misfired “authentication” of Mozart. Tonight, 7:30 PM, Scottish Rite Cathedral, 935 N. Dearborn; Saturday, 7:30 PM, First Congregational Church of Evanston, 1445 Hinman, Evanston; Sunday, 7 PM, First United Church of Oak Park, 848 Lake, Oak Park; 334-2800.