classic-mac-tools
Collection of scripts to bridge files from classic Mac OS to modern macOS and vice versa.
File associations
Converted files won't have any file associations as classic Mac OS doesn't use file extensions. I recommend using FileTyper to set the correct codes, here is a table with codes (or use TEXT and MACA for text files, WORD and MACA for MacWrite files).
Text files
Both txt/classic2modern.py and txt/modern2classic.py can be used to convert each line endings. Modern to classic additionally also convert smart Unicode punctation to ASCII equivalents and strip any other Unicode characters.