Lovely! Do you use the shape heads?
Yes! Those and the nice spacing of very closely-set measures are why a lot of us use Lilypond.
Are you trying to make a book like the 19c originals? Is there an example we can take a look at?
Well, I'm not involved with a book project — just writing a template for this style of music that could be used to assemble handouts or packets of songs.
I'm confused about what the page title should be if you have say three songs on one page, or does that not happen?
We only do two systems a page, so three never happens. But to answer the general question: here is a three-page sequence from the 1860 Sacred Harp, which demonstrates "Continued" headings and the format for a song that starts mid-page. (They're attached as 165.png, 166.png, and 167.png if you don't get inline images. Ignore the composer and poet attributions — it's just the song titles I'm worried about right now.)
Here is a two-page spread showing songs that start mid-page but do not require "Continued" headings. (30.png and 31.png; again, ignore the attributions.)
The goal would be to be able to write
Family_Bible.ly, Joyful.ly, and so on while remaining agnostic about where on the page the songs would begin — and then, if I wanted to assemble a handout containing two songs, to be able to write a separate file
handout.ly containing