Try this.
Use a pencil or whatever jammed into the mechanism to hold the cage out against the spring. String and attach the cable, tightening the pinch bolt only until it touches the wire and can hold it loosely. Manually pull out the cage, remove the pencil and let it move in by way of the spring. This will slide the cable back in the pinch bolt (unless you tightened it too much), and it should stay put when the FD is sprung in all the way.
Now, manually pull out the cage against the spring and tighten the pinch bolt.
You should be about as close to a spot on perfect as you could expect. If there's an inline adjuster fine tune using it. Otherwise repeat with a minor tweak such as moving the inner limit so the sprung position is shifted the way you need.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.