I'm a little late in suggesting this but I have the same boat, circa 1991, and Ward from Beneteau in S.C. is a great resource for specific design questions or locations of thru-hulls, etc. I believe if you sent him the numbers off the Beneteau plate he can help you with knowing what the original plans were. He's a busy man and email is usually best but I've had great luck. Google Ward from Beneteau and I think you'll find him quite easily.
We love our 35s5!
We love our 35s5!