Torque is what tears stuff up, not horsepower and any decent 408 generally has real good torque. If it doesn't hook up good you have no problem but if it does hook good and spits the shaft out it'll most likely take out the 727 with it so you'll not only be buying a driveshaft but rebuilding or replacing the trans too. It could even ruin the yoke on the rearend. Now how expensive is that $300 driveshaft looking!