Taking a poll about which drivetrain I should use

I'd just use the 74 drive train and put together a car to drive and enjoy.
A numbers-matching drive train is meaningless unless the car is a bone stock restoration, it sure sounds like you're planning a modified car. I fail to understand the value of matching numbers on a 318/904 car, it's not a Hemi Cuda after all. In 1970, 318 Dusters were common as dirt. If you really think the original drive train has any value, seal it up in plastic, stick it in a corner of the garage and trip over it for the rest of your life.
Anyone who takes offence at my comments, please remember that the OP asked for opinions, this just happens to be mine!