[gutvol-d] Custom covers for a book that has no original cover available?

I'm transcribing a book Harivamsha which has a PDF of the pages at archive.org but no book cover. I know I don't need to provide a cover, but I'd like to have one. While there is no book cover, there is some good art in the public domain inspired by events in the book: https://commons.wikimedia.org/wiki/Category:Harivamsa I was thinking of taking one of these images and putting the title and author on it using The GIMP and making that my e-book cover image. Is there any PG policy on this? James Simmons