Brake Booster?

Don't know if it will help or not. This set up was on a bracket car but I ran a 383 in a 73 swinger but instead of power brakes I used a manual brake master cyl. and had excellent brake pedal, nice and firm feel and no issues. The car had disc brakes on the front and rear drums, still have the car. Granted this was a drag car not street and the 383 is a low deck vs. the 440. I did have a shield under the master cyl. for heat deflection but as I said never had any issues getting it slowed or stopped after the traps. Good luck. Others have done this swap so I'm sure you'll get some resposes.