In all Commercial Districts, a non-conforming use that is listed in Use Groups IV, VI, VII, VIII, IX or X and not permitted as-of-right within C7 Districts, and which is not subject to the provisions of Section 52-32 (Land with Minor Improvements), may be changed either to a conforming use or:

(a)        to any commercial use permitted as-of-right within C7 Districts, other than those listed in Use Group V, in which case any subsequent change of use shall conform to the provisions of Section 52-36 (Non-Conforming Commercial Uses in Commercial Districts); or

(b)        in accordance with the provisions of the following table:

provided that such changed use shall conform to all regulations on performance standards applicable in M1 Districts, and that any such changed use or any storage of materials or products accessory to any changed use shall be located within a completely enclosed building. Whenever a use located within a completely enclosed building is changed to another use, no activity related to such changed use, including the storage of materials or products, shall be located outside of such building.