Convert from city block [South, West U.S.] to military pace [double time]

Unit Definition (city block [South, West U.S.])
The south west city block is an informal unit of distance popular in the U.S. A block is the average distance between street intersections in the rectangular street grids common in most American cities. The length of a block varies from about 1/20 mile (80 meters) in New York to about 1/16 mile (100 meters) in many midwestern cities to about 1/10 mile (160 meters) in cities of the South and West. (In New York and some other cities, streets running on one direction are closer together than streets running perpendicular. In these cities, people often speak of "short blocks" or "long blocks.")

Unit Definition (military pace [double time])
The length of a single step in marching (taken to be 30 inches for quick time or 36 inches for double time).