Definitely in favor of "A Holy Book." Gotta be clear on the pluralism.
Making the borders smaller would definitely help. I feel like it would be better if it all just fit on top of the original picture, but with the words on it already, that doesn't work. I wonder how hard it would be to extend the background blue and yellow beams from the FSM, and the clouds at the bottom as well, so that they go behind teh border, in place of the black.
Ultimately though, I'll probably just print out my copy on paper, and skip a fancy cover. I'll just have
"The Loose Canon. A Really Important Collection of Words. A Holy Book of the Church of the Flying Spaghetti Monster. First Edition"
as the title page. Formatted a bit, but very plain.