I split this into its own topic so that it wouldn't get lost on a post that was 8 months old.
It will be quite hard for you to find a legal position teaching in China at 70 years old. There are always exceptions in China but it seems to be that most of the wiggle room is for people in the 60-65 age range. There's also more wiggle room if you're doing something specialized to where that specialization overrides your age.
Can you do tutoring, private part time work, etc., theoretically yes, but you will still need a visa or residence permit. If you aren't getting your legal paperwork from your employer, then you are taking a risk.
It can't hurt to send out some resumes and see if you get any bites, but I would not get my hopes up. There might be some other countries out there that have less strict age limitations -- Korea? Japan? Thailand? Vietnam? I don't know. Not to be pessimistic but I think your chances of landing your first job in China teaching English at the age of 70 are close to zero.