Clois,
Brake line length has no effect on system pressures.
You are dealing with a non compressible fluid.
There is little flow involved, so any pressure drop calculations that are used for tube flow are not applicable.
Think of it this way: If you have a piece of steel tubing two feet long and you push it against the floor with 20 lbs of force, you get 20 lbs of force at the floor.
If you have a three foot piece of steel tubing and you push it against the floor with 20 lbs of force you still get twenty pounds of force at the floor.
(Plus the extra weight of the longer tubing of course.)