Painting the coils top yellow has been around for some time now. No one really advertised what paint they used. I know of one judge who would let it slide if done well. I saw one last week on a $100K Boss 302 that had sloppy paint lines. It made me question the whole car. We have a lot of "quick paint job" restorations here on the west coast as rust is less of an issue.
If you are going to do it, do it well. Otherwise, questionable work just leads to closer inspection of everything.