Apply some naval jelly to the rusty scratches; that'll stop the rust. A Good coat of wax will make it nice and shiny.

Or, lightly sand the rusty spots; fold some sandpaper and use the crease to sand just the rust off. Clean the area thoroughly. Get some Testor's model airplane paints in the little glass jars. You may have to blend a couple to get the right color but it works pretty well. Test on a scrap piece of metal. Spray on some clearcoat. Be sure to get a compatible clearcoat. Again, test on the scrap piece of metal, not the bike. Or, just apply some good carnauba car wax.

If you do decide to repaint it, don't powdercoat. Powdercoat is the devil to remove and if you ever want to convert the bike or heaven forbid, sell it, you'll be much better off with a regular paint job.

That's a decent frame with Reynolds 531 tubing and pantographs and lugs.