As an alternative to the authorization for an indebtedness provided by section 198.310, for the purpose of providing funds for the acquisition, construction, erection, equipment and furnishing of nursing homes and related facilities, and for providing a site therefor, including offstreet parking space, and making from time to time enlargements or extensions thereof, the board of directors may issue and sell revenue bonds. The revenue bonds are payable, both as to principal and interest, solely and only out of the net income and revenues arising from the operation of the facility, after providing for the costs of operation and maintenance thereof, or from other funds made available to the facility from sources other than from proceeds of taxation.