Gear ratio for 7 1/4

I would not put 5 cents into regearing or doing anything to a 7 1/4 'specially with a v8 and you want to pump it up some

Dakota is a poor choice as you'll have to cut off the spring pads and start over, and the bolt pattern is completely different. You'll likely have to change the axles, I doubt you could re-drill the 6 bolt pattern. The early Dakotas may have? been 5 bolt but you still need to rework the perches and I don't know about width. I bet they are wider

As said you could look for a later 8 1/4 and figure on maybe later changing the front over to 4.5 bolt circle