Judging from this rendering and the night one, I'd say it's probably between 600 and 620 feet. The main roof of the Austonian is 622 feet. This new tower looks to be about level with that point, even though its block's sea level elevation is almost 10 feet lower.
The Fairmont, seen here to the left, is 456 feet to the roof. And the Hilton, which you can just barely see peeking around the right corner of the new tower, is 377 feet.
