Make sure to take off your line and go in with the ends of it at least. I had some fun with mine and getting the right sized ends. You have two choices, buy the bulk line (cut to lenght, put your end on, double flare and install) or buy pre-sized line.
My $0.02 (for what it's worth) take a good hard look at all your lines. I replaced them all on my truck when I got into it. You will find that as soon as you touch it, they all show their age very quickly. If you got your bed off, now is a great time to do it. I did every line, including the rubber ones, and the ones on the axel. After looking at them good I was replacing 75% of them due to one thing or another, for the cost, and the fact that I know they are all good, they all got done. Metal brake line is cheap, few joins and adapters and you are set to go.
Bend them nice and easy too, you can get a tool that you roll them on, or use something that will make sure you don't kink it.