S13 Clutch Line Issues

[bmcnult19]

Alright so here's the deal... I'm rebuilding my S13 hatch and I've recently put in a new clutch line. I know the slave cyl is good, because it worked before I changed the line. The problem is that when I go to bleed it bubbles come out for days. I sat under it sucking bubbles out for literally an hour or two. Is it likely a problem with the master cyl? That's the only part I don't know is good.

BACKSTORY: I had two master cylinders, one from my old 91 and one from the new-to-me 92 that was still in the car. When I went to swap the 91's KA into the empty 92 I just assumed it was fine.

It's been sitting for over a week "gravity bleeding" and I guarantee when I go back the petal will sink to the floor with almost no resistance.

Also does anyone know if the master cylinders on RockAuto are any good? They're only like $20.