I want a Automatic with overdrive in my T-Bird

[Old Redneck]

Any one of you ever put an Automatic with Overdrive in a 56 T-Bird? If so what transmission and how much trouble was it? My T-Bird has the air cooled no lines going to the radiator. On the interstate my T-Bird needs a overdrive to run at 70 +. I need to talk to someone that has done this. I plan on keeping the T-Bird, I do like it very much.