In no event shall the assessment of the balance of the corporate property and capital stock of any company under §67-5-1203(b), in any year up to and including the year 1980, be less than the assessment of the shares of stock of such company for the year 1967, under this part, or, in the case of a corporation which is the continuing corporation resulting from a merger or consolidation, less than the aggregate assessment of the shares of stock of all its predecessor corporations for the year 1967, under this part.