i've just bought a 1994 zxr 400 as my first road bike, i've previously had 2 stroke motocross bikes so i'm no stranger to stripping down engines

i have yet to collect the bike but i'm trying to get ahead by getting as much info as i can on it.
here's my problem haha...
i've bought it as a non runner and the previous owner thinks the piston rings are gone but to save time once i've striped the motor i wanted to know where to get the parts from ready but i'm having problems getting the rings.
any ideas would be very much appreciated or other options i have...i dont mind modifying the motor but would like to keep price down where possible and reliability up as much as possible.
many thanks in advance scott.