You could try
https://www.cmsnl.com/ for microfiche and parts diagrams. See if the bike you have matches the parts on the parts diagrams.
If parts are rare there's also
https://japan.webike.net/ they have a lot of parts in stock and are situated in Japan so if anyone would have the parts in stock it'd be them.
My technique for my zxr400 (its a grey import) is to find the part number on cmsnl and then do a search on webike and get a parts list
then do one big order to save on postage. If webike dont have it then I try search engines and wreckers websites.