My 2 cents...

It's often quite difficult to get master links that fit every chain. I've seen many variations between manufacturers, so I always try to purchase 2 master links with every chain I buy. I also purchase my chains 4-6 links too long, that way you always have a spare piece of chain to carry in case of a failure. 4 links of chain and a master link doesn't weigh much, and will probably get you out of a jam.

Were it me, I would purchase brand new chain and sprockets a week before your journey. Ride the bike a few times to "break them in" and then be sure the adjustment and alignment were spot on before departing. I would put the old chain and sprockets in a box, and have them ready to ship should you need them during your trip. If not, you can put them back on when you get home.

Every day on the road, towards the end of the day, stop and lube your chain. #1 the rollers are warm and will soak up the lube. #2 Your chain will be sitting in a nice coating of chain lube while it sleeps every night.

If you ride in the rain, be sure to lube the chain before you stop for the day. Believe it or not, I've seen chains rust overnight after a heavy day in wet road grime.

Buy a HUGE can of chain lube, it's almost impossible to find at stores in China. Hitting the chain with engine oil is terrible for O-Ring chains.

Cheers!
ChinaV