They posted the site plan to the city's FTP site today for 208 Nueces Street. This is the 28-story office tower planned for the Austin Music Hall site. The building elevations start on page 21. The building is 387 feet 4 inches to the mechanical screen with 28 floors. That makes it 6 feet taller than what Austin Proper will be. This also shows one of the renderings of the building.
ftp://ftp.ci.austin.tx.us/ATD_AULCC/2015/150910/PLANS/AULCC_SP-208%20Nueces%20Street_PLANS.pdf