Is the 5-speed cable longer than the auto cable? I did a auto to 5-speed conversion and the cable with moving it over to the new hole just won't make it to the cluster.
I got a cable out of a 4-speed car, and held it up against my auto cable and they were the same. I can't speak for all of the -- but that was the way it was for me.
What you might try is unbolting it from the frame (under the master cylinder) and then connecting it to your gauge cluster. After that, when it's put back together -- rebolt it.