Try a smaller diameter master cylinder first to help it stop better, 7/8 or smaller
My S/P car has dual Wilwood calipers on the rear with the same size single Wilwoods on the front, dual 7/8 Wilwood master cylinders with a balance bar, stops fine at 150+ MPH weighing 2850 Lb. with me in it, stops fine on a short 1/8 mile track at 125.+ MPH.
I took the parachute off do to it not running above 150.+ MPH in the 1/4 mile so it would fit in my enclosed 24 Ft .race trailer better with more room in front of the car
Keep the hoses as short as possible also