Hi Pro transmission builder here....
If you google up Edelbrock TV adapter you will not come up with many pictures that fit your actual adapter. Maybe you have the wrong adapter type for your carb model.
The correct start and finish point for the pull of the cable is very important. Double check your model number and which adapter it uses. I could be wrong but it doesnt look right to me. The support bracket you are using is for the old th350 kickdown, it may be ok but doesnt really position itself very well for a nice cable entry.
The TV start point is the most important, pulling the moment the throttle moves, this jacks the pump pressure up from about 60-80psi to around 250-300. When you are cruising at only slight throttle opening, you will have only 60psi on the clutches if the TV isnt pulling and it wont hold diddly squat for very long.
The position of full throttle is still important but only because if it cant travel the full distance at full throttle it will wrench the outer cable on the ratchet adjustment, moving the critical start point back to bad slack position - your trans will then wreck itself on the next outing in short order.
PULLS the moment the throttle pulls - cant pull anymore at full throttle - is the correct and only way it should be set. If you have a problem with either position you have bad adapter angle issues that must be fixed.