NV4500 swap.

If memory serves, the NV4500 wasn't available until 1989 or so- by then they had gone to hydraulic clutch linkage, as opposed to your '84 using a mechanical clutch linkage.
Since you are converting from an automatic, you'll need to adapt the later hydraulic linkage and components to your '84, and then use the '89 and later NV4500 bell for a smallblock.
Be aware that the Dodge NV4500 came in at least 2 versions- one for the smallblock and one for the Cummins. There are differences to the input shaft that make them not interchangeable without swapping the shafts and associated hardware.