Rear line lock

Thats how I did mine, about 30 years ago, two control valves, with a switch so I could pick one or both. with a 2 step and a delay box.. Had to make a 2800 rpm chip for the 2 step, or use a variable resistor. Foot flat on the floor, 2 step holding it to 2800 (brakes won't hold much more)
actually worked really good. Brakes released instantly ( I was concerned about that before hand). 4400 turbo action converter. I had hooked up a brake pressure gauge, but it was too much to watch while staging, plus 2 pushes on the brake pedal buried the 1200 psi gauge.