I could be wrong, but isn't this the calculation of your maximum lift:

1kg ~= 35oz so 175oz/in = 5kg/in

8cm shaft = 3.15 inch

Max lift = 5/3.15 = 1.59kg

Edit: oh, are you trying to lift 1kg or 10kg? You mention both values.
I think even 1kg will be iffy to control as the quoted torque is peak torque. The actual torque varies over the step(?).