Being worth it is in the eye of the beholder I would imagine. And I don't know if it is the best way, but I repainted my 1973 Gillette long handled Super Adjustable with one of those vehicle paint touch up pens. So far so good.
I've never found the need to repaint the numbers in any of my vintage razors. However, if I were to get one replated, I would definitely paint the numbers. Not sure the best way to do it, need something really fine to get in there and some good enamel paint.
+1 on a good enamel paint. Use a super fine model paint brush, check craft stores. No worries about "painting outside the lines". Just get the paint in there, let it dry for 24 hours and carefully scrape off any pant outside the number depression.