Has it been confirmed that you have this condition?
If it is a structural deviation there may not be much that can be done to improve that aspect of the situation.
You’ll want to have 100% of the range of motion you can have with that deviation in structure. If it is 100% of your 70% of pull rom then having that 70% is your goal. Feed your ankle some slack within the situation.
Working up/down stream of the ankle so other structures within the system are at 100% rom heel cord, foot, knee, hip etc.
With sack being fed to your ankle the situation can improve. It may not be 100%, but to have 100% the available rom is the goal.
Have you watched any of the episodes on standing etc.?