I should have mentioned this sooner, but a program specifically adapted
for street organ work is the free program Rollook by Swedish amateur
organ builder Johan Liljencrants, available for download at his web
site, where you can also find many photos, diagrams, and sounds of his
own large organ:  http://w1.879.telia.com/~u87902212/

I have tinkered with Rollook just a little bit, but it is very
powerful, based on a piano-roll view.  It can filter out "illegal"
notes and move blocks of notes to other pitches.

Johan updates his program from time to time, and the price is right.

Mike Knudsen