To upload large files with API v2, you should use upload sessions.
One of our developers (Kannan) posted a rough example of how you would do this in this thread:
https://www.dropboxforum.com/hc/en-us/community/posts/205493536/comments/206447846#community_comment_206447846
(It looks like you already found that, but I'm posting this for reference for anyone else who comes along here.)
