Eric Kujawsky is not intimidated by big pieces: He likes organizing big concerts with his Redwood Symphony. And this week he’s taking on Berlioz — not the puny Symphonie Fantastique, but the full Requiem Mass, performed in Davies Symphony Hall with soloists and over 200 choristers. Sure he’s got to import 70 of them from New York (the Finger Lakes Choral Society and the Rochester Oratorio Society), and naturally he’ll be raiding more than 35 local Bay Area choruses for singers, including the full San Francisco Lyric Chorus. But that’s the only way to play the game, if you’re the ambitious Kujawsky. Challenging though the Requiem is, this special concert might turn out to be a peak summer event.