I Googled 'the lilly digest' and the second listing is 'How to Analyse(sic) and Interpret Financial Statements'. It contains many subtopics and maybe one of them will be what you are looking for.
My manager told me after our April inventory that my turns were X and I should work toward improving tmem to XX turns. Don't know where came up with the numbers!
The April issue of PPO gives detailed information on inventory and turnovers. It was part of the Wage and Task Survey done last year by nearly 300 Pharmacy Buyers. It might be a better barometer of where you should fit than some generic publication. I doubt if The Lily Digest would be a specific as to give you average inventory details on a facility of your specific size.