[Red Herring]

Be aware that when you rebuild calipers (and do a really good job) the pistons almost move to easily. This means when you try to bleed the system they move back fractionally when you release the lever (the suction part), giving excessive travel on the lever just as you describe. Once there is enough pressure to push them properly onto the pads and discs they usually say put and the lever firms up. I usually get round this by pumping the lever back and forth really quickly once the system is full and bled, this seems to get the fluid past the master cylinder before the pads have a chance to retract.