Question for engine experts

[j.fro]

I've heard that the heads on 99-01 3.4L engines and 00-01 3.2L engines are the same...
My 99 996 C4 has oil in the coolant, so I'm guessing cracked head. My plan is to swap in a used 3.4.
So, if the bottom end on my old 3.4 is good, can I put my Boxster S 3.2 heads on and get some added displacement?? (Hopefully a good port/polish is in the budget).