Over the last 5 months, I have been working to restore the Harvard Classics (now in public domain) for Kindle. I've been able to put up more than half of the individual volumes (the rest are already available for free and, thus, cannot be sold by me) through KDP.
Now, after having done all that work, I would like to make the entire 51-volume set available as a single book.
I have done my editing with Sigil, then converting to MOBI with the command line Kindlegen software before uploading to KDP.
Here's my trouble:
Kindlegen converts the file just fine.
The MOBI file is nearly 75MB, which exceeds the 50MB limit (which I found last night).
The EPUB file is only about 19MB, but fails in the conversion process when I get it uploaded.
Thoughts on what I can do, either regarding the EPUB or the MOBI?