The height limit in the Vista is 80 feet, although there was a slight variance for the Hilton. I agree with Spartan - this building will probably be 4 or 5 stories - along the lines of the Arnold School of Public Health. I'm sure it will be a much bigger building, however, in terms of square feet. They will probably need 400,000 to 500,000 square feet for the School of Business.
On another note; while it seems odd to me that the DMSOB (sounds bad, I know, but too long to spell out) will be located on the "research campus", I think it will work well, especially with USC"s prestige in international business. I'm sure thee can be some significant partnerships between international companies locating in Innovista and the MIBS program. This is great news all around. I don't know why it will take 3 years to build, though.