Most important step is to bench bleed the master and make sure all of the air is out. Then the rest should be cake.
Start with passenger side rear bleeder then jump to the passenger front when the pedal is still down.
You should have steady brake fluid flow after 2 bleeding that will force all the air out.
Never underestimate a faulty master cylinder new out of the box. I have had 2 bad ones in a row.
If you bleed the brakes for an hour and still have a crappy pedal chances are the master cylinder is no good.
With a bad master cylinder it will leak internal and not have good pressure to the rear or front and the pedal will be soft.
Also make sure the brake pedal push rod is the correct length so as the piston in the master cylinder reterns all the way back.

Hope this helps