Ideally they could fit it on the two huge blocks bounded by Trinity and Red River in between 7th and 8th Street. This would mean tearing down the Salvation Army and Caritas
(and moving those services to another location) as well as buying out the vacant block owned by the Methodist Church. I believe the height limits are mostly 60 feet for these two blocks so you would have to get a variance (easier if the City and University are involved) or maybe go underground 20-40 feet.