Tips on touch up painting a frame and identifying colour on a vintage GT?

[Norris47]

Hi everyone, been following this forum for a while but only just gotten my first vintage GT that I want to work on. The one that I’ve picked up has a lot of patches of frame rust and was thinking whether it would be viable for me to use my dremel to sand down the little areas and painting on colour on top by hand. I don’t feel uncomfortable doing this and I’m not bothered about a very clean finish however just trying to find paint that would match the colour of this frame as close as possible.