You really want 13.7 N-cm (0.137 N m) to have enough torque but they might do.
The 7.5° step is more of a problem, most use 1.8° step motors so your positional accuracy will be 1/4 of what most people are using. You will need to supply at least 24-30 volts to the stepper motors.
Bob Morrison
Wörth am Rhein, Germany "Luke, use the source!" BLOG - PHOTOS - Thingiverse
