If it's mostly for the street I can guarantee you will need to swap gears. My guess is the old motor was stock stroke engine so it liked low gears. If your stroker is 500+ hp and torque you don't need very low gears to be faster than it was with the old engine. Like CB said on the advantages of a 904. I'm not sure at what power level you need to go with a billet snout on the converter but I know I've read of guys breaking stock steel snouts. Maybe Rob can answer that. Another person to check with for a trans. is Chris at Andrews racing. He's also a member here and another great guy to deal with.