As far as I know, there was no facts book or other related publication issued for the Darrin. There are some Service Bulletins and those, combined with the owners manual and Darrin parts book (called Parts List), issued May, 1954 comprise the available non-advertising literature for a Darrin.
Several years ago, the Darrin owners manual was reprinted. It's an excellent copy and the only notation of the reprint is on the back page.
I've not seen the preliminary OM mentioned, but given that KF did this for some of their other models, it would make sense that a Darrin version could exist.