Transmissions do not have a HP rating. They are rated on torque and it seems to me that they are rated at 335-350 ft lbs. Although they will hold up to much more than that. Ted Lyons has one in his supercharged 5.0 Bird, and Steve Griffith has one behind his turbocharged 5.0 Bird. Both cars make between 500-600 ft lbs of torque. You should be ok.