Yes, both years operate by combination of vacuum/electric circuitry. A cable system is possible, I did it on a different '70 GTX than the one I own now many years ago using the same cable that was used on the '69 setup, which is simply the cable for the passenger side fresh-air cabin vent. It was rather crude, today I would have the skills & tools to do a much better job than the "meatball surgery" I did then! An aftermarket choke cable would probably work better & would undoubtedly be cheaper these days. Finding all of the correct pieces to do the factory vacuum setup would likely be time consuming & costly, so unless you're wanting a factory look I'd go with the cable.
