Brake bleeding questions...

[Earl Filter]

I put new brakes on my '77, including new master cylinder, hoses, calipers, rear wheel cylinders, etc. The only things not touched were the proportioning valve, hard lines, and booster. I bench bled the master cylinder well (or so I thought), and have bled the lines a bunch. The brake pedal goes almost to the floor still. The brakes work, but not until they get towards the bottom. I'm pretty sure that this is an air-in-the-line issue, but I'm open to suggestions. Now that it's all together and this is the problem, what should I do? Any tips on bleeding the master cylinder again? I seem to get a push of fluid at the calipers with no air bubbles or sputtering of fluid. Anything else I should look at as well?