A Capella Recording of Mozart's "Lacrymosa"? Where can I find one?

I'm looking for a high-quality, a capella recording of Mozart's "Requiem". I need this piece to be on-tempo (preferably a machine-generated whole-number tempo, i.e. 90 bpm) and on key, without accompniament. Anyone who knows where I could find one or is willing to produce one is GREATLY appreciated. Message me with questions.