All I can say is what I would do next. I have read every word of every post and I'm not just shooting from the hip. I'm thinking about this like it is my car and my money buying the parts. When I go over the course of events, one event sticks out in my mind; when you cracked open the front bleeder for good measure. That's when a good day went bad.

Replace the wheel cylinder at the corner where you first started to bleed the front. If you were doing it in the proper sequence, that would be the passenger front wheel cylinder. Joe and Dennis, just do it. Don't ask why, just replace it. It's what I would do and I have a journeymans card(went to college for it LOL) and have fixed over a million machines for GM in and out of the factory. DO IT!!! That's the way I would tell the apprentice and he does not usually do it. He would wait till I wasn't looking and change the distribution block!
If you are feeling ambitious, replace both front wheel cylinders.