69 notch back opinions needed

So I have the notch, good body-frame. I’ve been toying how to put together and want to hear the groups opinions. First option I have is the complete drive drain out of a 72 Duster, /6 w air 3 in the floor and 8-3/4, it was a twister. Second 318 ac auto 8-1/4 out of a 74 Dart (big bolt pattern) third 400 ac auto out of a 73 Chrysler. /6 I don’t know the condition but have 4 more. 318 and 400 where rebuilt awhile back (20 year ago) but no miles. I want a nice driver that gets decent millage, something I can let my wife drive (stick no problem for her). Let’s hear what you think. Pros and cons. Thanks