The article still says 300 units for Three Light, which is basically the same as Two Light. The footprint looks about the same, so unless these units are significantly larger, or there is another mixed-use component, I wouldn't expect anything drastically larger.
If they are planning on going condo, they might be looking at higher end finishes and amenities, which could add a bit to the price. A Target could add to the price, but I still don't see how it could total $300M. Maybe the price of the office building (H&R Block II) got added in?
For comparison to another Cordish project, all of Ballpark Village Phase 2 in St. Louis is listed at $260M. It includes a 29 story apartment tower, an office building (don't know if there is anything official, but renderings look like a 9 story building with ground floor retail), an 8 story 216-room hotel, plus another 2 story retail/entertainment building.