4 speed auto into '65 Barracuda?

The big question is why change what you got? I cruise my 65 cuda w 318 904 all day, everywhere no problem! If it needs rebuild, do it correctly, get it done well and enjoy the ride! If driven respectfully gas mileage is decent so why go to hassle to convert to odd ball transmission? Actually with my 4bbl gas mileage is decent if one stays out of 4bbl and into the smaller carbs......JMO