In twenty years of restoring pumps, airmeters etc. I've developed colors that work for me. It was done, as said before many times, by matching color charts with decals, globes, signs.....It has taken years and many miles.....My answer, to this question, is to find a color that you like and use it. Life is way too short to waste on such an issue. My opinion as always. Paul www.severngaspumps.com by the way.....we do not share color codes with the public so please do not ask....