Looking over the posts in this thread, I thought I would suggest the use of brake "bleeder" fittings. I've used these on several of my cars. Fitting has a "built-in" check valve that comes into play when the bleeder screw is loosened only a 1/4 turn. Allows you to bleed the brakes "the conventional way" by pumping the brake pedal. Old fluid evacuates the line and when you release the brake pedal, the internal check valve prevents backflow of air into system. Seems somewhat risky, but these special "bleeder" screws really do work.