Have you tried talking to the sailmakers? They will have had the accurate IJP & E measurements to at least give a clue.
Look at the makers name on the mast section. Z Spars were very helpful with me for my mast repair on the Jouet - even though they hadnt made the section for years.
I may be able to help you with the info.
We have a 72 dufour 35 , and with it came lots of detailed drawings and spec. sheets as supplied with the boat from new .
give me a call on 01782 751140 and Ill see if I can help