Yes, but it is ugly, prone to user error, not future-proof, and will likely be a maintenance headache. Having said that:
Rename content/dir1/page2/index.md to content/dir1/page2/__index.md. Note that the new file name begins with two underscores. The file name is actually irrelevant, as long as it is neither index.md nor _index.md.
If it were me, and I were transitioning a site from < v0.56 to v0.81, I would live with the new URLs, and create 301 redirects where needed. In the long run this one-time effort will be well worth the expense.