Install new master cylinder without bleeding?

As mentioned, you must bench bleed the M/C which gets fluid on both sides of the pistons. Plug the line openings while installing. Connect the lines carefully. If you have been careful, the only air in the lines will be at the line fittings. Depress the pedal and hold. Crack open both fittings, then release pedal. 90 percent of the time you will be good. If not, then you will need to bleed all four wheels.