I have just completed a full nut-and-bolt restoration of my '67 250SL coupe where I changed its color. When I had my car all the way down to the bare welded body structure, I decided that was the time to choose a new color. Mine left the factory in 158 white-grey with a 190 dark grey top and a caviar (silvery dark grey) interior. It is now 268 dark green, matching top, parchment interior with light green carpet.
I would not change colors in anything less than a fully disassembled body because you will find that body color is everywhere . To do it right, remove everything from the engine compartment, dashboard, door pillars, wheel wells, etc.; it is amazing where you will find body color. There are bolted on pieces that get painted body color, too, separately. (the cowl air flapper comes to mind)
Changing the color of the interior is a task, too. There is a dozen or more of small, hand-fitted pieces of fabric in and around the dash board and windscreen alone. (Carefully save and label every scrap of old fabric you remove to use as patterns for the new color.)
The finished car is now exactly the color combination I wanted. It was a lot of work but the end result is georgous (to me!)
Ray
(268)Green 250 Coupe