Some alternatives.
- Take frame to a powdercoater who has done bikes. He will sandblast off the paint, using plugs to protect the bottom bracket and other openings, then powder coat it in the color of your choice. He should have pamphlets showing dozens of colors. Powdercoat is more durable than paint, looks okay although a little "thick", and you can apply decals on it. The end result will look good although it won't pass for the original MB-1 paint. Usually they are single color coats. That should cost $100-150. It is possible to do a multi color job but I'm not sure most places are able to do so. He should be able to fill the dent before coating.
- Take frame to a painter who knows bicycles. A lot more expensive, price also quite variable - I think $400-600 would be a "good" price. But ask around. He can fill the dent and apply decals, and the bike can look fresh from the Bridgestone factory circa 1991 when it is done.
- Clean the frame very well, treat the rusty dent (wire brush off loose rust then treat w/ rust convertor and paint), use touch up paint (like model paint from the hobby shop) on the scratches. I've seen incredible results but need skill and patience.