I asked Trevor Legate some years ago about paint codes for Viking Blue for my 289FIA Cobra replica.
He directed me to a particular photo in one of his books that was a very close match to Viking Blue. I looked for late model cars that were a close match to that picture, "late model" so that I could easily obtain a paint code.
The one I settled on just happened to be a Ferrari colour on a friend's 308 GTS.
The code that I used is "AZZURRO MET. FER 505/C" if that's any use to you. You can see the result in my gallery if that's of interest.
I am very pleased with the colour, FWIW
Cheers!
Glen