some info on a 440

426 to 440 is .070" over...perhaps it's too much overbored, but the only way to truly tell is to sonic check the cylinders...but there are several other things that can contribute to overheating, as you surely know.

That being said, I'd be inclined to agree with ScampTramp...have the radiator looked at, it may be either too small (not enough cores) or may have blockage. And also as alluded to, the fan may not be pulling enough air...clutch fans and shrouds work wonders...