I'm apparently one of your long-lost relatives. We lived on a farm 5 miles north of South Plains in the 50s and 60s. My grandfather was J. Alexander Deavenport who married Genelle (Nell) Baker before moving the family from Lockney to Boulder, CO where my two brothers and I were born. Like you, I also have a copy of the book you mentioned. It's really quite interesting.
Another of my distant cousins, Daniel Kuettel (Switzerland) is doing genealogy on our family and I've been helping as much as practical.
It looks like there is a fairly healthy mix of our relatives digging around on ancestry.com. I just started looking at the posts so I'm sure to find more things of interest.
I wish I had kept up with our family in more detail. My email address is email@example.com
if you want to get in contact.
Have a nice day and thanks for the post.
Dennis Deavenport (Houston, TX)