To migrate your Reading List from Safari to Instapaper run:
git clone https://github.com/ivaxer/migrate-safari-reading-list-to-instapaper.git
cd migrate-safari-reading-list-to-instapaper
virtualenv --python=python3 env
. env/bin/activate
python setup.py install
migrate --help
migrate -u instapaper_account # -p password if set
Script uses only Instapaper's Simple API, which doesn't require premium account. Therefore migrate
can't sync read/unread statuses and skip already added articles.