Figure $200-300 per axle for setting gears (yes, you need to do both ends, but you knew that already.) Parts? A masterpack from Drivetrain Direct with new gears, bearings, seals, etc. runs around $450. Going from 3.07 to 4.10, you'll also need a new carrier for the front D30.
Now would be a GOOD time to consider putting in traction aiding devices, aka limited slip or locking differentials. My opinion is that if it's a daily driver, go limited slips, something like a TrueTrac up front, and an Auburn in the rear (assuming that you have a Chrysler 8.25.) If it's not a DD, think about Detroits.