In case bonds shall be issued, such bonds shall run for not more than thirty years and bear interest at a rate of not more than the maximum rate of interest prescribed by Kan. Stat. Ann. §§ 10-1009 and shall be executed, and the aggregate amount thereof shall not exceed the cost of said memorial, and the site thereof, and the expenses of said election, nor shall bonds be issued for more than two percent of the assessed valuation of the county or the city in which said memorial is located.