Re: v6 to v8 swap, how hard?
a whole bunch of headache. first of all motor, then wiring harness, computer, all the exhaust parts from a v8 and possibly a set of motor mounts. I have never swapped one so I'm only taking a stab in the dark to give you an idea.
V8 birds where i live are pretty cheap and I can't see the upside to swapping in a V8 into your bird when so many are avail to buy.
My idea, junk your broken 6 and buy a V8 model. you'd be happier in the short term and on the road quicker. It never fails no matter how much access to all the right tools and parts and friends to help....when it all goes back together something will go wrong.
If you still wanted a six banger, try to find a S/C model. They have the same power as a stock V8 I had one pass me the other day and the sound of the supercharger was pretty cool.