I can't believe manufacturers still sell heads and say the springs are good to X amount of lift. Valve springs don't work that way, and AFR come with shitty springs to begin with. Call the cam manufacturer and buy the springs they say you need for the cam.
he bought the car already with this setup and have all the receipts for the motor etc etc etc, and he asked me to come look at it since im the area mustang guy lol. but yeah thats what i suggested was to just get springs from trickflow or frpp springs that are suitable for his cam