I discourage any idea that a "code" will produce anything like what you hope for, in any car color, including Grigio Biacca. Well, if you don't mind that the red, white, or whatever is miles away from what you thought you were getting, you may be happy with that red, white, or whatever.
I am convinced that the only way to get a color that is exactly the color you want is this:
Find a highly expert paint mixing genius.
Find a sample of the color you want, or which is at least close.
Have the expert (him or her, hereafter referred to has "him") do some hand-matching until they duplicate the sample you provided, or the appropriately modified color you asked him to achieve.
Paint a test panel, let it dry, take it out into the sun, and decide if it's what you want. If not, have your genius do some more mixing until you produce a test panel that makes the angel's sing.
Use the computerized color-matching camera which the paint-store has, and which has been calibrated to work with the paints they sell, and scan the hand-mixed, painted, dry test panel.
Using the formula produced by the camera, that is correct for the brand of paint that your store sells (and no other brand at any other paint store), mix enough paint for your car.
Spray a test panel, and confirm it matches what you want. If not, your genius can tweak it.
Paint your car.
I've seen pre-determined formulae for Grigio Biacca that come out refrigerator white, pale green, pale blue, and faint gray, all of which are deadly wrong. GB is a sort of "ivory" color, and referring to it as gray is a red herring.
The concept of a mixing formula works if your car is less than about five years old, and your body shop is repainting the entire car after some sort of shunt. It won't be exactly the color that your car had when it was new, but it'll be close enough that (if you painted the entire car) you won't notice.
Modern paints from modern paint companies are so different from what was used on the Touring cars that no computer will have a formula that works.
I found a few spots on my 59 Grigio Biacca Touring 2000 that had been hidden from the sun since new. Specifically, under the chrome top hold-down brackets on the rear deck. We removed the chrome hold downs, and polished up the old lacquer to its original lustre. Having been spared from the sun and elements for 50 years, we had an original patch that we could use the computerized camera on. This produced a formula for the store's paint, and we were jubilant with the results. We just did the same thing with my current 10204 project, using patches found under the chrome door rubber bumper guides on the rear door face.
If you have no original paint in perfect condition to scan, you're better off having your genius mix until you see something you're happy with.
I could possibly get a formula by having my painted car scanned, but it is highly unlikely your paint store will have the same paint as used on mine, and thus the formula would be useless, or at best, a starting point.
Early Touring cars did not live in the digital era.
Carson City, NV
59 102 Touring (first Alfa $500 running)
65 Sprint GT (2nd Alfa, $500 daily driver)
102 Sprint (never did anything with it, but wish I had)
74 Berlina (first new car - now certainly rusted into oblivion)
61 Giulietta Spider G-Prod Race Car (where is it now?)
84 Spider Veloce (rarely drove it, so sold it)
86 Quadrifoglio (Dull car - no more 115s for me)
1971 Montreal "The Full Monty". Fair winds and following seas
59 102 Touring Roadster - restoration complete, enough Alfa for any rational man. Or irrational, for that matter
Oops. Add to the "present" list, 10204 01488, 2000 Touring Roadster project
Two 1946 Stampe SV4C (c/n 294 "Rocinante" - wife's favorite airplane. RIP), and c/n 235 "La Bon Temps Femme" (gone to a new home, but never forgotten)
Zlin 50LA (+9 -6 gees, titanium spar, 1200 lbs, 260HP rumored to now be in Brazil)
1946 Luscombe 8A
Starduster Too (recently spotted at the Nevada City, CA airport - over 20 years and an entire continent separating it from our stewardship in Binghamton, NY)
1955 Cessna 170B (wife taught me to fly tailwheel in this)
64 Mooney M20E ("Rambo". My faithful steed for over 40 years) Over 55 years old, and just returned from a trip to Argentina in him
Newest in the fleet
1967 Piper Super Cub on Wipline amphibious floats (a true "all terrain vehicle")
2010 Triumph Thunderbird
You can snap roll an Alfa only one time...