Switched to A5 portrait. In landscape it stretches the image to fit the
width, and that causes a lot of longer tunes to become too high to fit
properly on the page.
Build the book in a separate build directory. The build generates lots
of .abc files and so forth, which it is convenient to have elsewhere
so you can ignore them. I did experimend with \abcinclude, but that has
a lot of expectations about the files being in the current directory.
If a tune has multiple titles, pick the first.
Adjust abcm2ps options to preserve the line breaks in the ABC.
Jim Hague