Ronnie Spain is still working on the book. At the moment he's doing his version of the "One Lap of America" to gather information (he's planning on going to Massachusetts, Connecticut, New Jersey, New York, Alberta, Washington, California, Utah, Colorado, Florida, ...).
For the first book, he limited the information in the book. This time, he'll try to put in as much information as the publisher will accept.
BTW, he's now personally seen 103 of the original GT40s.