NEED TO FIX FRONT BRAKE LINE METAL
In a pinch, I agree, use a compression fitting. But that is even harder than doing it the right way. After cutting the line, you have to have it perfectly round. By working with the already rusty metal, you are now fatiguing the metal. Then add on the compression, and added weight, and you get yourself a weak point.
The easiest way is to by the right length line or lines (It is far better to have more than less), the couplers (if needed), and any special adapters you may need (ie 3/16 standard flare to 1/4 bubble flare.) Take with you the ends and a section of line. The line is not that expensive ($7 for the longest.)
Start running the line, one section at a time, making sure to keep the ends on the end. When you need to make a bend, DO NOT make a tight bend that crimps the line. Discard the line if this happens. If you have a tool, use it. Other wise use you hand to make, gentle bends. Connect one end and connect the couplers, if used. When you get to the other side, wind the excess around a spiral. Secure with wire or existing retainers.
This is way safer than a compression fitting, and not all that hard. Remember to bleed the brakes