The small numbers of boats built..at equally small and world diverse yards is the reason...there is no formal international or for that mater individual governmental body like in the Auto industry mandating safety in which the information you desire is required to be kept.
Sail Boat construction up to the late 60 was all one off art so to speak...not until mass production from the larger producers of fiberglass boats did any semblance of consistency develop in regards to construction specifications being kept for the general public to access...And even into the early 90's it wasn't like it is today with manufactures opening up there information like they do today over the Internet.
It takes hard work and a personal investment of time and money to root out and publish the info you seek...Books like that are the least lucrative endeavor a writer can under take....Go for it..
....we will all... if not buy your book at least thank you for it at the library...
I see this is a very old thread...maybe the OP is in the trenches working on that book...LOL..