Canon, really great job, you did in fact succeeded in capturing the main essence of Haussman architecture... More variety may be better but I still think that when flying low at 400 kms/h we won't notice that.
As already pointed out, yes the zinc roof shall be mainly dark grey on the extremity and blue grey close to brighter area (those hit by the sun if any that day^^).
With regards to your question on use of your previous blocks vs your new ones, here is attached a quick global map of paris whereby I tried to identify type of block architecture by "Arrondissement" :
The numbers are the number of each arrondissement
The blue stripped zone are those where haussman architecture exists at WWII time
The red stripped zone are those where "suburbs" architecture may have been at WWII time (for the one in 3rd arrondissement it is an area called "the Marais", a very old part of Paris absolutely not modified by Haussmann)
the white lines are the biggest city roads of paris called grand boulevards, they should also form multiple branchs of a star starting from "place de l'