A998 Trans in '66 Dart

so, I am running a very mild build 318, and am simply looking for something with an overdrive that would be reliable and i don't have to chop the car u. if the tail shaft is longer cutting the drive shaft is not an issue. with that information, does anyone want to provide their ideas. i have read all of these, the majority of my driving would be mostly around town, but would like to be able to keep up with traffic on the Xway. This has a peanut rear end in it. Not a go fast, just a cruiser. Thanks all.