Zongshen cb 250 (zs172fmm-3a) where can I get spare parts?

Hello, I have the following problem:

I need spare parts for the Zongshen CB 250 (ZS172FMM-3A) engine, which are unfortunately very difficult or even impossible to find.

I need: timing chain + guide rails for the timing chain.

Maybe someone has an idea where to get these parts for the model and I thank you in advance for any help.

Please no annoying comments like: just leave it if you can't find it etc.

I can happily do without people like that.

Thanks 🙂