I've been meaning to build ~exactly this experience, but for the 1952 Encyclopedia Brittanica Great Books of the World collection and its experimental index Syntopicon [0]. Would love to know more about how you OCR'd or otherwise ingested and parsed the raw material. I have a physical copy of the books, and I found some samizdat raw-image scans and started working on a custom OCR pipeline, but wondering if maybe I could learn from your approach...
[0] https://en.wikipedia.org/wiki/A_Syntopicon