Re: line voltage limits
110.4 has voltage specs, but they are not very specific. Specific voltage limit information is going to have to come from the equipment that you are installing. That would be more restrictive than 110.4 as equipment is required to be installed in accordance with it's installation instructions per 110.3.
+10% is probably acceptable for heating elements, and motors, but not much else in my experience. You may need to move a tap on a transformer somewhere...