Not impressed looking for advise

[IMPALAMAN1]

1968 impala.... heavy car.... oe was power drum brakes.... not the best but atleast they stopped the car....

fast forward to the 4 wheel disc conversion.
corvette disc/ disc master, dual 9" diaphram booster
disc/ disc prop valve
new 3/16 line the entire car.
hurst roll control (maine reason for the disc swap.... drum didnt work like i wanted the line lock to.)
front rotors... slotted and drilled 11.75"
front calipers, factory 1969 impala
rear rotors 1979 trans-am slotted and drilled i believe they are 11"
rear calipers are the cadi seville with parking brake

i have bench bled the master till my arms fell off
next tried mighty vac.... no go
next tried traditional 2 man... you kick the pedal nad ill crack the line. no go after 3 hours of roamin under the car.

next took it to a shop and had it pressure bled.... said he got a little air bit nothing to write home about.

so the symptoms are... no and i mean no panic stop possible.
you can feel it grabing and it will get stiffer as it goes to the floor.
then the last half inch or so..... it grabs and starts to slow.... it will eventually come to a stop..... there is no noticable nose dive like modern vehicles..... i would like more pedal and it stop on a silver dollar.... shoot ill even go for for a manhole at this point.... the dime seems so far out of reach it isnt funny.