I gravity bleed my system. I replaced the m/c, hard-lines, calipers, rubber lines and wheel cylinders. No issues, i did do it more than a couple times though to be sure.
I cracked one line at a time until i got fluid, starting from the back, it takes some time. Went all around a couple times until i had a good enough pedal to drive. Got things hot, nailed the brakes some, brought it back and bled them all again. been fine ever since