They must have added the elevation files after you posted that, Hill Country. They're listed there now.
They're files 034 and 035.
https://www.austintexas.gov/devreview/b_showpublicpermitfolderdetails.jsp?FolderRSN=11056288
458 feet 9 inches to mechanical penthouse roof.
435 feet 6 inches to main roof.
422 feet to the highest occupied floor (39th floor).
61 feet 9 inches to the 6th floor podium.
Those numbers are the ones measured from the southwest corner of the building at West Avenue and West 5th Street which the rendering below shows. You can see that staicase in the building elevations, so for sure that elevation is above street level.
