Do you have a copy of, or know anyone who has a copy of Achtung Panzer No.6? You can get it at: http://www.rollmodels.com/ or http://www.greatmodels.com/
The book is well worth the $32 you will pay for it at roll models. It not only has 20 pages devoted to the Ferdinand//Elephant vehicles, but it is a must have for modeling any variant of the Tiger tank. I think there are 60 or so pages just for the Tiger I
Anyway, there are some nice detailed pictures of the top of a Ferdinand. There is also a nice set of 1/35th scale plans for top, front, back and side views. If you can’t find the book or can’t afford it, let me know. I will try to scan and email you the plans in the book.
Good luck with the project.