You might contact Paul Bennett at Bennett Brothers Yachts (www.bbyachts.com).
Paul was the president of Stevens Yachts until selling the company in the late 1980''s. Bennett Brothers Yachts also maintains the Stevens 47 club supporting Stevens 47 owners around the world in maintaining their yachts.
The Stevens 47, the predessecor to the Hylas 47, is a larger version of the Stevens 40. Both were built in Taiwan by Queen Long Marine - the boatyard that also built the Kelly Petersons and now builds the Hylas line of yachts. Paul, more than anyone else, would know the particulars and history of the Stevens 40.