feature request: Volpiano transposition

This request comes from a student user, who transcribed a number of melodies into Volpiano but mistaking a c-clef for an f-clef, and wishes there were a way to simply change e.g. c-d-e-f-g to f-g-h-j-k without having to retype the entire chant. I don't know how many people this would be useful for, but it could be fun to have...