You should flesh out the history maps a bit more. I usually work backwards. It is easier to cut and remove buildings. Buildings also have rooms added as time passes and lots fill up leaving only light wells when all the land is used up. The growth of some cities are well documented, like Boston and New York City, USA and London, England. An organic grid like this is very believable in my opinion and though you might end up with more allies and lots are cut and sold in the old parts of town. I really love how the final product is turning out.