Windy, I have used Chevrolet by the numbers, Author Alan L. Colvin. My particular book is 15 yrs old now. I do believe these reference books have been updated and broken down into more specific sub categories over the years.
There is also a website called nastyZ28.com that I frequented when I was restoring a 2nd gen 73Z. This particular web site has a wealth of knowledge on second gens, just about anything you would need or want to know on a second gen.
http://www.nastyz28.com/forum/index.php