brake help please

Personally, I wouldn't use that method...by itself. And here's why; take 6ft of clear plastic 3/16 line. Put one end into a clear quart sealer, and anchor it in there, so it can't blow out.Cover it, but do not seal it.
Into the other end pour a small measured quantity of brake fluid.Say 1.0 ounce.Now raise this end up and see how much of it comes out the other end.Well? how much came out?Hmm. Ok now put some air pressure to it. Now how much came out? Now examine the line. You see all the tiny droplets stuck to the tube? The surface tension of brake fluid makes it stick to the tube pretty good.
So if you really want to get it out, you will need to follow the compressed air, with a chemical wash. And every last molecule of the chemical wash will need to come out as well. Brakleen is the chemical of choice. It evaporates well in open air, cuz it has a really low flashpoint.That's why you have to get it out; so it doesn't reduce the boiling point of the new fluid. So now you will need to blow that out. But how can you know it's all out? You can't.
Furthermore, unless you have an air-dryer on that compressed air system, you will be blowing air with some unknown amount of moisture in it directly into your system. How can you know it all came out the other end? You cannot.
So, what's my point?
The point is this; no matter what method you use, there will be contamination.
For me, I feel the least amount of problems is to just pump new fluid in from the top. Not gravity. Pump it in with the pedal. Do it in the proper order, until it runs clear at each station. Then pump a little more out.
If you depend on gravity, the new fluid will roll on through, passing over those molecules stuck to the side of the tube. Pressure bleeding tends to scour the sides some.
I've never had any come-backs using this method.