Great job, at this point, I would put the rear valance on and check for proper fitment. When I did mine, I did not do that and I ended up grinding out the welds at the tail panel, removing the section that goes from the quarter panel to the trunk drop off and making that piece more narrow so that my quarter panel and rear extension would line up properly and my valance would fit and have less of a gap between it and the quarter panel before welding that piece back in.
You are doing a great job on your car and I have been following it, keep up the good work.
Tom