I would try the shorter tire which should pick you up about 300 rpm. With the overly aggressive first gear in a 540/Torqueflite combo (assuming you run one!) you might lose on the bottom what you pick up at the stripe. What was peak torque on the dyno sheet? 5800 rpm might be a tad low, and a converter loosened up to gain 400 stall may put you up around 7600 rpm with a 102 roll out and 4.56 gears. Mine gained 300 rpm on top when loosened up.