I'm, ehhmm, planning something new for my s4r.
Which year(s) had the metal tank that will come close to fitting on a 07 s4r? I know the fuel door/hookups will be wrong, I'm more interested in the hinge and latch being in the right place.
AFAIK, hinge and latch positions are all the same.
The late model IE tank with the largest cavity on the bottom, as was fitted to '01 -'05 Desmoquattros (S4 and S4R) would be your best bet.
Pretty sure there were some of the 2-valve Monsters that used that tank as well.
This thread will help:
http://ducatimonsterforum.org/index.php?topic=541.0 (http://ducatimonsterforum.org/index.php?topic=541.0)