You are limited in choices for what you are doing. The easiest would be to locate a floating/hanging pedal setup from any 70's or 80's mopar and use a cable. A good choice would be the cable from a slant equipped truck since the cable would be longer than one sourced from a car.
If you wish to retain the floor mounted pedal you will have to locate the pedal assembly from a 64-66 273 a-body or from an AC equipped slant a-body from those same years. I have been thinking of making an adaptor to convert the twisting motion of a shortened factory rod to pull a cable so that I could retain my pedal and kickdown while allowing more carb choices.
Mid 60's c-bodies also used a floor mount pedal. It is wider than the a-body unit, but you could likely use the entire pedal/bracket to get youself to a cable system.
A picture would help so we would know what you have to work with. I would also suggest you download the 66 service manual that is somewhere on the fabo site. It shows very detailed pictures of the throttle linkage in the transmission section.