Gidday Piero.
I hope this helps.
This is based on British Standards. it is NOT the metal flake used on the 2 tone red and silver. It is the single color only.
Signal Red British Standard code : BS 381 or 381C. I think the 381 C was a very old code. 381 seems to work
Paint code 537
I used this code on my bike and was very happy
a good place in the UK to enquire is E-paint .co.uk
hope this helps Aussie bradley