for each torso, base.count=torso.count
What condition are you using? You need conditions which pick instances. For example "Base -> Compare Instance Variable".
If you are using System conditions like "Compare two values" - they don't pick instances.
Also, linking with Pin and instance variables is an old method. In C3 you can use hierarchy - it will be much easier. Add Body as a child to the Base sprite. You can select which properties will be synced automatically, for example the angle. And you can use "Base Pick Children" condition to pick the Body sprite.
EDIT: Container is another option. Or use both the container+hierarchy for maximum automation.