PORTLAND – When Toshiyuki Shimada wraps up his work at the Portland Symphony Orchestra in little more than two weeks, he’ll be devoting more time to his search for long-forgotten music tucked away at the Vatican Library.

Under a licensing agreement, Shimada intends to release a series of compact discs carrying the seal of the 500-year-old library. He plans to draw on a variety of music but he also hopes to discover long-lost musical treasures.

After two trips to Rome, Shimada has realized the enormity of the task of sorting through thousands of manuscripts in the collection.

“It’s really overwhelming. That’s the whole thing,” he said. “We need more people working on it. I’m working as hard as possible.”

Help is on the way. Shimada’s Trinity Music Partners is in the process of hiring additional researchers to assist on the project, said Joe McNulty, a Portland accountant who brought together investors and helped to arrange the deal.

The licensing deal between the Vatican Library and Trinity was signed a year ago. Since then, Shimada has been wrapping up his tenure at the Portland symphony while taking on a new job as conductor of the Yale Symphony Orchestra and trying to get the ball rolling on the Vatican music project.

Shimada, who serves as Trinity’s musical director and chief creative officer, plans to make his third trip to Vatican City later this spring as he continues to sift through the library’s manuscripts and musical opportunities.

Already, he has identified a manuscript by Italian composer Alessandro Scarlatti that dates to the late 1600s.

The piece, written a capella for the Sistine Chapel choir, is documented in some scholarly works. But Shimada can find no evidence that it has been performed in modern times, providing a hope that he’ll uncover long-hidden works.

The piece will be included on an Easter CD to be released next year, he said. Trinity’s first release, of Christmas music, is due this fall.

Shimada described holding precious works from the library’s collection, including a manuscript from the mid-1500s and the choir book from the Sistine Chapel that contains thousands of chants and polyphonic music.

“I was amazed when I saw for the first time the endless library stacks in the manuscript vault, and in the basement,” Shimada said, recalling his first visit.

The five-year licensing agreement between Portland-based Trinity and the Vatican Library calls for a portion of the proceeds to be returned to the library.

Shimada, who already has 15 CDs under his belt with labels including the Vienna Modern Masters, said the first compact disc from the Vatican Library collection will be performed by the Moravian Philharmonic Orchestra in the Czech Republic.

“No one has done this type of project. So we have been learning as we go along. I feel we’re confident that we’re ready to go,” Shimada said.

Meanwhile, Shimada is preparing for his final performances with the Portland symphony. He’ll complete his 20-year run as maestro on May 2 when he concludes this season’s Tuesday classical series with a performance of Verdi’s Requiem.

Portland is in the midst of a search for a successor to Shimada, and has narrowed a field of candidates which initially numbered more than 200.

Guest conductors will wield the baton next season, with the new conductor expected to be named around the spring of 2007.