4.6 HEAD SWAP

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...

thats a hunk of change right there.
 
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.