Since I have the 2014 Vision Line Big Boy and I'm pretty sure the mechanical design is identical, I can say it almost surely will not clear 2.75" from the center rail. Mine needs 3.0" from the center rail clearance, and the MTH Premier Big Boy needs almost 3.25" from the center rail.
Would you be able to measure the height from the railhead to the lowest point on the front edge of the boiler, i.e. the point that would first contact anything like the steampipe to the front cylinders? This is his Lionmaster Challenger from an earlier post just as a sample, and if you look close, the steam pipe can almost clear the top of the trolley track (if the trolley wasn't running, of course), so if the Visionline is slightly taller in that spot, then it may fit. I know I'm grasping at straws here lol, but I'm just trying to help my buddy out. I could also raise that track up with another layer of cork, but it's ready for ballast at this point.