By chance, are you in a state that does emissions testing?
If so, you will never get that past the smog Nazis.....
if not, well, some day you might have a BIG headache when your state adopts emissions testing.
My question is why did your friend pull the 3.4? I would save it for a CJ project later in life, or Craigslist it for money to put towards a proper engine swap.
If you are dead set on using the 304, check out Advanced Adaptors and Novak for transmission and transfer case adapter information.
Wiring will be an issue too, get a complete diagram for your current setup and listen to Fweaky too!