Being the fastest on the street and not breaking a stock rear end shouldn't be used in the same sentence! With your pickup being light in the back, it's going to take a good 4 link setup and a strong rear end (Ford 9") to make it hook and work! Big horse engines are fun, but you've got to be able to get the power to the street, too. A balanced approach of horsepower and a good working chassis would probably be your best approach. About 375 to 400 horse is about all that the stock parts are going to handle, even at that level the stock pieces have a shortened life expectancy.