Whats the proper length speedo cable

What is the proper length speedo cable for a 69 Plymouth Valiant 4 door car. I have found them at 60", 63" and 81". I don't want to have a bunch of cable curled up under there. Yes, I could pull the old one and measure it to be sure but That is not an option at this point. I would like to get one in here and be ready to exchange this when the car is down. I am sure someone has this info readily. Thanks,Bill