Making kickdown lever for carb

1. Does the lever on the trans need to move forward or back to operate correctly?
2. Is your cable coming at the trans from the rear or from the front. It will determine if you need to pull the cable or push the cable.
3. The center to center on the trans lever would dictate the center to center of the lever on the carb. If the carb is 1.5 inch CL TO CL and the trans lever is 1inch CL to CL the trans lever will stop before the carb is at WOT.
4. The carb lever will work best if it starts at 8 and goes to 4 or visa versa. That gives you the most liner movement of the cable.
5. The trans end should do likewise

I would look at kits that are for sale on line and reproduce what they have done.

Best chance of a good outcome