This is a usefull website for rough planning:
Great Circle Mapper
Mind it does greatcircle routes only, not via airways. So the actual legs will be longer than shown.
Not sure if yr A/C has ETOPS approval. And I'm not familiar with the range of the B733, not sure if it has the range for the legs.
I guessed M .74 for the speed.
I planned around Russia, because the overflight permits are expensive. China may take a long time before you get approval.
Go around the Himalaya's, not over them.
And make sure you get all the overflight- & landing permits well before you go.
Have fun!