Yes, "A Keen Eye" is out of print. To find one, you will need to find used being sold somewhere.
Books you can find, I would recommend "West Highland Cattle: The Grand Olde Breed" by John MacKenzie Anderson, it gives some detailed history of the breed, written in 1986, it has some reprinting of writings from the 1700's . $20 at AHCA
You could also subscribe to the American Highland Cattle Association's "Bagpipe" subscription, it is $30 a year for overseas.
Also "The Highland Breeders Guide" $12 at AHCA of course you can read this online at
www.HighlandCattleUSA.org ..... But it is nice to have the book in your hands.