'63 Plymouth, 523" around 750 hp. weighs close to 3200 with me in it. I am running 4:10 gears, letting the engines torque take care of the launch, I was wanting the car to MPH, and to hold down the finish line RPM's. I am happy with it. 6:20's, 110 in the 1/8th, thats at sea level here in Coos Bay. Been 9:80's at 140 in Medford. With your "new trans" and the proper convertor, your car will fly!!! You should have a totally different car performance wise, don't be afraid to try a set of 4:10's!