another option...
Take your bike to a local autobody or autobody supply shop. Nowadays, most will have a digital scanner "gun"; they simply aim the gun at your bike and it reads the colour and gives them a formula to mix the paint for an exact match. It's amazing. I've used it for bikes and cars, and the paint match is superb. It's automotive paint, so it's durable.
You can get the paint made up in a spray can, or in liquid form to dab on the scratches with a small brush. More expensive than nail polish or Testor's, but a much better match.
All vintage, all the time.
Falcon Black Diamond
Gitane Tour de France
Kuwahara Sierra Grande MTB
Bianchi Super Grizzly MTB