Here is a catalogue from 1977 which I hope might be of some help - apart from the isometric view on page 3 it does not really have much in the way of drawings though.
Is yours the cruiser version, or the racer with two cockpits?
The forward end of the single cockpit on the cruiser is 2' further aft than on the racer, giving a lot more room in the aft cabin.
The base price for the racer in 1977 was GBP 34,884, while for the cruiser it was GBP 34,274; the deluxe versions were GBP 37,050 for the racer and GBP 39,070 for the cruiser.
Very clever man Alex, he had a garage and boats were his hobby, I remember him designing and building the 37 and I think he was hoping to get onto the Admirals Cup Team but another boat was chosen instead. He also used to do a lot of the mouldings for the Vancouver when the Dandridge's were building them in Newhaven. After the boat business went wrong Alex did stuff like motorcycle fairings then he got very big in GRP waterslides and I used to do a lot of the supporting steelwork for him at that time. That business also went wrong but he's still around and doing stuff and I still see him occasionally, although he must be somewhere around eighty now still drives his Porsche like the wind.