Hey Phil
I'm in the same boat mate, owning a '98 900ss, i know how awkward it is getting parts. I've had to find out whats interchangeable, and the 750ss and the 900ss are more or less the same bike. I know the front guard are the same, and other small bits.
Best thing to do mate is go on
www.ducati.com and download the spare parts for both models (e.g. 750ss & 748) and check the part numbers on what your after.
You can also try these sites (mail-order sites), found good stuff for mine:-
http://www.ducati-kaemna.de/uk/katalog/index.html http://www.techtwin.com/eng/eng_techtwin.htm Hope this helps m8
Steve (tont)