I need to change the ring and pinion in my 85, currently 3.07. I'm thinking of going to a 3.54. I've been told (and read) that the 3.54 would be sufficient vs. the 3.73. I only drive it as a daily driver and want to retain as much MPG's but still add a wee bit of kick. Will I need to recalibrate anything due to the different ratio so the speedo reads accurately or will it be OK on its own? Or should I just stick with the 3.07.