Have you thought about giving a Python 2 to Python 3 converter a try? Since it's just a handful of files it could actually work pretty well:
https://dev.to/rohitnishad613/convert-python-2-to-python-3-in-1-single-click-2a8p

Here's the docs on the 2to3 library:
https://docs.python.org/3/library/2to3.html