Cool bike. I once had an '83 Nighthawk in a dark blue color.
I'm no paint expert, however, a good painter or paint supplier should be able to come up with something that closely resembles that Alfa concept car. Keep in mind that the car is Alfa's show piece that has been travelling the world and getting photographed for magazines. That means that Alfa probably spared no coin in making the paint flawless (and photogenic). I think you're right about the red base and pearl top coats, although Alfa probably would never divulge their "secret" show car color. It is not likely to be the same as a production color and the paints are probably top-shelf, top-dollar show car items that would not normally be associated with a production car.
Nevertheless, you can probably come up with a color that is close enough. Good luck and please post pictures when its done.
FYI, the Alfa Romeo Colour you are after is the Rosso Competizione 202, hopefully that will make it easier for you to find the relevant paint from a manufacturer.
I have seen pictures from a German autoshow, where there were 3 or so Alfas painted in the same tone, remember that the cost pr. litre was insanely high! But good luck with your project
The paint is offered, from Alfa Romeo, only on the 8C Competizione and it is my guess that it will be the most popular of the 4 colours available, appearing on circa 350-400 cars. The other types are Alfa Rosso, Yellow and Black.