Make sure you measure the length of the outer jacket. The inner cables(overall length) could measure the same, but if the outer jacket is longer, that will effectively make the cables too short once installed. The inner cable AND the outer jacket need to be the same length as stock.
I ran into this exact issue with my 73. I used one companies front and rear cables but their intermediate cable was too short. The rear cables had a longer outer jacket they my original ones. When you attach the front of the cable to the frame brackets, that puts the cable in more of an arch and pulls the inner cable end back too far. I ended up buying a longer intermediate cable from another company so I could get everything hooked up.