My '98 Boxster's (70k miles) engine just failed

. Catastrophic engine failure, i.e. the intermediate shaft went haywire. I'm still discussing with the dealer and Porsche NA on who should pick up the tab, though the car is out of warranty.
Meanwhile though, should Porsche NA not be accommodating, I'm considering putting in a used engine. Might as well give it a little extra power then by exchanging with a 2.7 or 3.2l, right? Has anyone done this before? Is it 'plug and play' or are some modifications required? Any idea of cost?
Thanks!