You say you're using a "stock style" master cylinder. Is it a disk/disk master or disk/drum?
I got the MC/booster combo from O'reilly's and I ordered it for disc/drum.
That's your problem. You will never get the brakes working properly if you're using a master cylinder designed for rear drum brakes when you're actually using rear disks. You NEED a Disk/Disk master cylinder. That will solve your problem.
Nope
The only difference is reservoir capacity, just check it when doing an oil change, top off as needed and the residual pressure valve in the rear brake (front port) outlet, which he's already been told to remove.