Or you could have gone and bought a line with fittings already on it, bent it and installed it in the time you have been jacking around trying to flare and rig the rusty line. Have you considered that if the line corroded to the point of a leak, the entire length of it is suspect? Many times steel brake line rusts from the inside out, since in this country, almost no one ever changes the brake fluid (DOT3 and DOT4 absorb water, BTW). Same reason I won't use an open container of brake fluid.Even today, people are religious about changing engine oil, but almost never change brake fluid.
Honestly, your story is all over the place....selling it, keeping it, have a buyer, going to keep it.....I'm worn out trying to follow this.
You should ask lilbowtie about resale on clean non-"image" cars. Personally, I don't see a red on red regal bringing $5K , unless you find a buyer that thinks 22K miles means it's the same as if it were 2 years old with that mileage. We all know that sitting most of it's life is not really good for the car. There will be plenty of worn-out parts on it due to age, not mileage.
But I do sincerely hope you find a buyer that appreciates it for what it is, since it seems that you are not in a position to really devote a lot of resources to it.