Hi, I'm actually working on this exact problem, I'm macronizing and publishing texts that are Latin only. I recently published Apicii artis magiri Cae libri X aka De Re Coquinaria, I'll be doing many more books over time, but if you have a specific request I'd be happy to move it up in the line.
Edit: for reference, this book contains 6 words of English, 1 is copyright, the other 4 are "this book was printed in"