Helping out a friend!

Hi,
I'm looking for some information.
A good friend of mine is looking into buying a 70 duster with a /6, i was wondering what it would take if he wanted to install a v8 at a later point.

The ad says it already sits on a V8 K-Frame so that is a great start. On the images he was sent it looks like it has 7.25 rear axle, if he wanted to upgrade to a 8.25 is this a simple swap or are we talking shortening driveshafts and moving spring perches?

Also, what tranny would most likely be in a /6 (it is an automatic), and would the tranny need to be swapped to fit a v8 (most likely 360), any other things that we should keep in mind?

Any info would help, if he gets it we'll have another FABO member on our hands LOL