289 40 over rpm intake 600 edelbrock carb DOOE 351W heads 194,160 ported, roller tip rockers, MSD6a...duals, hipo manifolds

I like driving the automatic but want more power/torque speed?
everyone here suggests changing the gears. I have the stock 3.0 now. I want to install AOD so this thing doesn't run so loud on the highway. This car will never see the track, but it does see the entrance ramp to the freeway...what gears should I drop in... and If I go up to 3.56 or more and AOD, did I just negate the lower rpm I was looking for with the aod???
lastly, are the gears hard to install?? I installed the motor an tranny....
thanks