What cables and crimps did you end up with?
Followed the recommendation of @AKNick and went with the Steelon nylon coated wire @ 120 lb:
https://www.berkley-fishing.com/ber...teelon/steelon-nylon-coated-wire/1060696.html
And matching connectors:
https://www.berkley-fishing.com/ber...nector-sleeves/connector-sleeves/1012020.html
Guess I need to run a few numbers. I may have assumed 120 lbs would be sufficient, and have a margin of safety.Don't think you will stretch that cable.
600 In Oz servo with a 4" double arm will result in less than 20 pounds tension. You have plenty of safety factor.