The appendix to the Kingdom book is where I started my research on this topic two years ago. As I read through it I soon realized that what it does is admit that there is no historical evidence for 607, but instead much evidence that would - if anything - discredit that date. Of course, the book is 20 years old. Surely if any evidence to support 607 had been discovered since then, the Watchtower would have been shouting it from the rooftops. Instead, as Blondie points out, they have been virtually silent on this topic ever since....
No Apologies (of the if I find out its not the truth, I will leave class)