[mr48chev]

1. Do you have have a matched system designed for one car or do you have a mix and match system with front calipers and rotors for one vehicle, rear calipers for something totally different as they came with the axle and a master cylinder that may or may not match one or the other?

Mismatched calipers, brake lines that are the wrong size for the application, master cylinder bore that is the wrong size for the application or may have the lines hooked up to the wrong ports.

Unless you are just flat using the wrong method to bleed the brakes I'd think that you have the air out of them.

All brake systems have some sort of residual valves to hold a slight pressure in the lines. The old original systems had it built into the master cylinder and the drum drum master cylinders have a residual valve behind the seat for the brake line. That's that little rubber piece you see in the hole in the seat that has a little spring behind it. That is on factory rigs with the master cylinder on the firewall. Most modern systems have the residual valve and proportioning valves built into the combination valve that is usually a few inches from the mastercylinder.
It's bedtime as I have to get up at 03:00 for work.