its decision time for you. to use a stock stroke 3.31 even at 425hp level on the street you will have to rpm the motor. witch will move you away from friendly street stuff force bigger gear to take advantage. no big deal if you rarely street run it. were as the 4.00 will achieve this much easier and still be friendly no matter what heads you use.. you wont hurt either pieces at this level. and 500 in not a big deal for the cast crank. the stronger piece i dont have enough experience to say but i have beat the holy living hell out of a stock 340 steel crank and it not be a issue. i have worked with the stock crank and the stroke and both are fun to drive and race. rpms are harder to maintain and inches make you feel like a king. rpms with gear are fun to hook up and listen to at idle or winging it.