Hi I have been reading this thread with interest. It is a difficult one, I have noticed where you may be going wrong. The original plate needs tidying up, you have some camera lens distortion. look up Barrelling and Pincushion on Google. The verticals on the plate need tidying up, the perspective to vanishing point was pretty good.
I have noticed that you were interested in doing a long street, this is fine but having worked in London the streets are actually small little blocks of architecture. There are examples of georgian architecture using long streets but not in London.
You need to incorporate some architectural rythmn. This would be having breaks between the houses to incorporate side streets. Dave mentioned a park, this would introduce a area of green. Why is a area of green important?
London pre 1666 was built up so closely that the city could not breathe, there was pollution and a excess of buildings. After the great fire Sir Christopher Wren was charged with rebuilding the city. He designed the buildings to be built of a light colour to introduce light, he also gave the city park areas where residents could escape the miasma. Also as a fire measure there were fire breaks which is why the streets are wide.
If you put in city blocks into the perspective line it would give the matte a sense of rythmn, the human eye likes this, greenery in a picture actually relaxes the eye, this would also break up the harsh lines.
The key to doing this successfully is to keep it simple, look at the matte work on league of extraordinary gentleman.
Keep the height of the buildings in as the buildings were built tall.
Keep away from the night matte concept, every matte painter reaches a plateau where they run out of steam and then they suddenly do a night matte. Night mattes are too easy to fall into.
In summary,
Rythmn
colour - green
spacing
sort out the original plate
keep it simple
I would also suggest no projection on this matte till it is finished.
You have some good ideas and I am eagerly looking forward to more,
Regards and respect
Rich