Yes, definitely go with 4.11 gears. I have an aod with a higher stall lockup converter in a 64 Fairlane. With the original 3.25 gears and a 25" tire it would foul the plugs under seventy mph in od. That was with the stock converter and stock 5.0 generic roller cam. I have since put in the 4.11's, locker and 2200 stall lockup converter along with a hotter cam.

Biggest problem with the aod's is setting up the throttle valve linkage. No problem if you get it right but you'll puke the transmission if you get it wrong.