A domestic mutual insurer, after being authorized to transact one kind of insurance, may be authorized by the commissioner to transact such additional kinds of insurance as are permitted under Section 27-3-6, while otherwise in compliance with this title and while maintaining unimpaired surplus funds in an amount not less than the amount of paid-in capital stock required of a domestic stock insurer transacting like kinds of insurance, subject further to the additional expendable surplus requirements of Section 27-3-8 applicable to such a stock insurer.