Lot's of time and money. Probably be cheaper to just swap a new motor in. Off the top of my head...intake, throttle body and plenum, air intake, heads (of course), timing chains, timing cover, computer for 4V...
you can put 4v heads on a 2v block theoretically but it wont give you any benefit in performance, it will probably just make it alot worse. Get your 2v heads ported instead. good bang for the buck.
i have all the parts for the swap just laying in my den. well everything but the computer. i am thinking about swapping when i put my bottom end in this spring/summer