455 running 210-220 at idle in 100 degree weather

3-5 psi at idle? Sounds like you have an oiling problem as well. Was the car running cooler before the cam and port job? Did it still have that 750dp on? Different camshafts can mess with valve timing and raise or lower the dynamic compression. Do you know your compression ratio? What octane fuel do you run? Try a higher octane and see what happens.