Decided to jump in on this discussion.
This is Andy Schank and I am the one who is going to be painting Michael's car, and I think we are looking for the color that is on the car in two top photos in post #4 above. I have seen that color on Sprints from that era (usually all faded to hell like the link below) Is that by chance Cobalt Blue AR 324? it is not Bluette or Medio Blue-they are not that dark.
Google Image Result for http://bringatrailer.com/wp-content/uploads/2008/03/1958_Alfa_Romeo_Giulietta_Sprint_750_Bertone_101_F ront_1.jpg