Roger, bear in mind that the 700R4 has a 3.06 first gear. Put that in front of 3.89's, and you have the first gear equivalent of an M21 Muncie in front of a 5.41 differential. I have 3.70's in my '34, and it doesn't need any more "punch" in the lower gears. If the tires stick, the acceleration is insane!