I have a 1963 Impala SS with a 355 engine and TH350 transmission. Looking to upgrade to 700r4. Transmission shop is recommending that I change rear gears to 4.10 to get the best performance from the transmission. Car currently has 3.42 gear. Looking to drive the car in highway from time to time. Currently the TH350 is pushing rpm`s to 3000 when I hit 70 on the highway which is why I want to go with the 700r4. What are your thoughts about going with the 4.10 gear and 700r4?