^ Six years? Try 12. Godzilla and the Lost Continent was supposed to be released in 1999.
And even if the first North American rights to the manuscript have reverted back to him (is that common? I've never heard of there being a time limit, just that you sell the publication rights), he still wouldn't be able to publish it without Toho's consent since Toho, not Cerasini, owns the rights to the characters.
Unless Random House gets the rights back, I highly doubt the book will ever see the light of day. The best we can hope for is to ask him for a synopsis.