That's probably not unreasonable. I know 5000 Yonge, a 20'ish storey tower, is slightly over 300 ft, and it has no roof treatment. So just proportionately I'd guesstimate a 30 storey tower to be about 450 ft, plus mechanical, and then Telus has that weird roof thingy with the glass extending up another two or three floors. Low 500's seems about right