No projecting sign shall project further than the inside of the curb line or be less than eight feet above the sidewalk, nor project beyond the property line at the street or alley more than six and one-half feet measured from the property line of the street or alley at a point eight feet above the sidewalk, except that such sign may project an additional two and one-half inches for each additional foot of height above the sidewalk. However, in no case shall such sign project more than eight and one-half feet beyond the property line at the street or alley, nor further than the inside of the curb line. (1964 Code §701.17)