I hate that gray color because it looks like shiny primer to me, but I am also not crazy about the color of either of my W123s. I like Silberdistal which is a very light green metallic.
Do the disassembly and reassembly yourself. Painters are notorious for masking things rather than removing them, or if they remove them, losing parts while the car is apart. Take as much off as you can so there will be minmal masking. Consider that the ultimate paint job was at the factory because they shot it when nothing was attached. If you can get close to that by removing the two layers of body side moulding, door handles, lights, grille, bumpers and the tougher items which are the trim around the windows and sills and the front and rear glass, then you can get a really clean paint job.
A trick to not removing the front and rear glass is to raise the outside lip of the rubber gasket and wedge sash cord underneath. This will leave the outside lip of the weatherstrip off of the body and you can shoot underneath it. When it is time to pull of the masking, you just pull out the sash cord and the outside lip of the gasket is now sitting on new paint.
By the way, a good paint job would not be considered a modification. The Silberdistal will not work for you because it was not used with blue interior. Look at the chart.
You can see the colors here.
http://www.astralsilber.de/