If you don't have a leak, replacing the brake lines won't solve the problem although I am definitely a fan of replacing old brake lines. I like using the copper nickel style lines. They are softer and easier to seal.
I have a cheap double flare set and I could never grasp the tubing well enough to do the flare. I have since obtained a better set and I can do flares no problem. The good set has a heavier clamping setup. As an experiment I put my cheap tool in a vice to help with the flare and it worked.
I would say that if you can get a good pedal with two quick pumps, it usually means a shoe adjustment problem. Also if you put the parking brake on, that usually shortens the stroke. It would be good to try as an experiment to see if you then get a pedal.
With no leaks and no pedal and properly adjusted shoes, I would think you have a master cylinder problem.
