I was in the same boat. Same Continental radio, had a late 90’s Alpine deck installed when I purchased the car, and someone cut the factory harness. I used butt connectors like the link below. I have a soldering iron/heat shrink and spade connectors, but have never had an issue with butt connectors on an install like this. Easy and clean. I also tapped the ashtray for the lighting. I know people will say solder and heat shrink, but I think it’s overkill here.
https://www.amazon.com/TICONN-Connectors-Waterproof-Electrical-Automotive/dp/B07HCPFPD2/ref=sr_1_2_sspa?crid=5VJWSN288FQ9&keywords=butt+connectors&qid=1585189599&sprefix=Butt+%2Caps%2C217&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExVFJZUVBIOVhDOFY2J mVuY3J5cHRlZElkPUEwNjg3MzYwRU5NODBSRDNZOENXJmVuY3J 5cHRlZEFkSWQ9QTAzOTQ1MDkxVUZMQ1hMWlRXWDBKJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==