Members with 4 wheel disc systems: Can you lock your wheels?

The hydroboost was powered by a Saginaw pump. Lots of OEM Chevy trucks used a Saginaw pump with hydroboost so I figured that I'd be okay using it for a vehicle that weighs 3900 lbs rather than 7000.
I never could get the HB to build pressure. Later on I saw that the PS cooler had a kink in the return line so I'm not 100% sure of where the blame lies. I was so frustrated with the effort, I just removed it and abandoned the idea.
Here are a few combinations that I've tried:
11" front disc 2.6" caliper, 10" rear drum. 1975 A body brake booster. Disc/drum proportioning valve.
12" front rotor, 2.6" caliper, 10" drum. 1975 A body brake booster. Disc/drum proportioning valve.
12" front rotor, 2.6" caliper, 11.7" Dr Diff rear discs with 1.5" single piston caliper. 1975 A body brake booster. Disc/drum proportioning valve.
12" front rotor, 2.75" caliper, carbon metallic pads. 11.7" rootr with 1.5" single piston caliper. 1975 A body brake booster. Disc/drum proportioning valve.
Same as above without booster but with 15/16" iron, 15/16" aluminum, 1 1/16" and 1 1/8" manual master cylinder. Disc/drum proportioning valve.
12" front rotor, 2.75" caliper, 11.7" rear rotor, 1.5" single piston caliper, drum drum distribution block, 1975 A body brake booster, modified pedal for increased leverage.
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. Hydroboost unit with 1 1/8" master cylinder.
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. 1 1/8" manual MC.
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. 15/16" manual MC.
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. 1975 A body booster, 1 1/8" MC.
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. 1975 A body booster, 15/16" MC.
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. 1975 A body booster, 15/16" MC, electric vacuum pump.
Now the current setup is:
13" front rotor, twin 1.58" piston calipers, 11.7" rear rotor, single 1.5" caliper, drum-drum distribution block. 1975 A body booster, 15/16" MC, electric vacuum pump and storage tank.

Yeah....I have tried LOTS of combinations.