Brake suggestions

No leaks anywhere, all new lines, hoses, master, distribution block, calipers and pads, shoes and drums, I believe everything is new. It has an 8&3/4 rear end out of a 68 Roadrunner, so all brake hardware back there is Mopar, I believe 10x2.5 inch stuff. The front is the disc brake kit from APD. I can't say for certain what master cylinder it is, as I went through about 7 trying to get one that didn't break or leak on me.

When I had left it, It just really needed to be bled but no matter how much bleeding I did, it was hardly working. I re-parked it halfway in my driveway and half in the street above the gutter to try to get it as level as I could since my driveway is slanted, and after bleeding the rear my helper told me it was very tight. I got air bubbles out of the passenger rear and not much out of the driver rear but I was told it was tight so I went to the front. As soon as I bled the front passenger, he said it got much looser. I assume that from all the pumping for the back that the front just had pressure and me bleeding it let it out and it got loose, however there were very few bubbles in the front passenger and 0 in the front driver side. 

I drove it around the block and I'd say it's working about 70%, enough to stop it but definitely not on a dime, more like a golf green if I'm honest. From not being able to stop it from rolling down a driveway to stopping from 30 mph, it's quite an improvement, but hardly where it needs to be. At this point, should I just keep going with the bleeding process even if I see straight fluid, or is there another spot to check? 

And on a side note, my driveway is slanted, I'm not on any hill but it is slanted perhaps 10-20 degrees, and since I got more air bubbles out when it was level I'm assuming my driveway had enough slant to make a difference. would there be any advantage to pulling in backwards and having the rear be a few inches higher than the front? It wouldn't put the wheel cylinders above the lines or master on the firewall, but it would be better than having the front up higher and creating a greater distance height-wise between the wheel cylinders and the master correct?

It is possible to bench bleed a master while in the car. The difficulty is getting the car level front to back and side to side.

Have you tried a power bleeder?

Have you tried any other type of bleeding method? Other than the conventional two person pedal down bleeder open, then close bleeder, pedal up, do again until pedal is solid, no matter how many times it takes.

how long did it sit between assembly and bleed/drive?

I think you are saving no time at all by not removing the master cyl and bench bleeding it. It will take longer, lots of fluid, and might not work, even. Mounted in a bench vise, levelled with a level, you can use short lengths of brake line to direct fluid back into the reservoir. Tighten into the ports, run the open ends into the reservoir, below fluid level. Then bleeding is done with a very small amount of fluid, just what's in the reservoir. Fat screwdriver in the piston and push with your hip until zero (0) bubbles. Even the tiniest, microscopic, air bubbles are gone, after 10 minutes of pressing slowly, releasing slowly.

Even a pinhead, or pinpoint, size air bubble you will feel with your foot. Absolutely zero air bubbles is the goal.