Glad to hear about your wheel base being equal on both sides, your tracking issue now would appear to be a "non issue"...Your right, it's great when a good plan comes together.
As far as body work and paint goes, it looks like you have that under control...It's amazing how many people faint when they hear that the cost would be up to 12K...but when you factor in the cost of paint material (about $1,000 minimum for quality products), all the man hours it takes to make a vehicle straight...then to have the ability to put a paint job on that lies down flat and has a lot of shine...and then cutting and polishing takes between 30 and 40 hours...it adds up rear fast. I did a frame off build not long ago and my bill was close to 25K...the customer was complaining the whole way through the build, but, I did what he told me he wanted.....I tried to keep him informed on a regular basis as what was going on and as always I kept a daily log a to what happened on his vehicle...towards the end of the build he started to understand...and when the build was finished, he was extremely happy.
$4K is a very reasonable price...you should wear a grin from ear to ear...what color is it going to be?
It seems that all that's left is the rear bumper, have you checked the alignment of that yet?