If we’re being precise, Block 71 is the City of Austin’s assigned number for a 1.75-acre downtown block owned by the University of Texas and bordered by West Seventh, Colorado, West Sixth and Lavaca Streets. But more importantly, it’s also the presumed name of developer Trammell Crow Company’s planned mixed-use complex, set to transform the site with a 36-story office tower, retail, restaurants, an…