[With regard to any county which is required to operate on a countywide system of road administration as described in Section 19-2-3, this section shall read as follows:]
The board of supervisors of any county in the state in which there are county road bonds, seawall bonds, or road protection bonds outstanding which were issued for the purpose of building bridges or constructing public roads may, in its discretion, in addition to all other lawful uses, use such county's share, or any part thereof, of the funds heretofore or hereafter derived from the tax on gasoline and the road and bridge privilege tax for the further purpose of paying interest and principal of such county road bonds heretofore issued for any of the said above stated purposes. However, nothing in this section shall in anywise affect Section 65-33-45.