I don't have the book, but I read the version when it was still available for free before it was published (on the website of the author). It is very akin to the 1920's setting. I mean that we have the feeling of a historical setting with little fantasy (excepted for the corruption of the old ones). There is a strong emphasize on the church of course.
I think it would be quite difficult to adapt it to the Hyborian Age (but who knows?).
Paradoxically, I would say that "Secrets of Japan" (1990's setting) would be easier a setting for, say, Khitai or a remote far-eastern Hyborian country.