If this tower featured a podium built out to the property line, roughly equal in hieght or even up to five stories taller than its neighbours, then a step back to the tower portion, I beleive the transition in height between properties would be much more successfully accomplished. As it stands now, despite the differently articulated facades, the lack of a physical seperation between podium and tower in terms of massing would present a sheer surface rising 45 storeies into the air, providing a somewhat jarring transition in the streetwall. Building out to the property line, including a stepback and maybe shortening the tower by at most 10 stories would, I think, provide exactly the tall/short, new/old contrast you allude too.