Deck heights are different I think that's basically the only difference in the blocks. They're modular so I'd think everything would swap over. Wait to see if someone here knows if you need the intake from the 5.4 too.
The PI heads from a 5.4 will work. I have a set I need to put on my car now. The only difference is that you will need 10mm bolts for the timing chain cover. The 4.6 heads use 8mm bolts. You may need new valve covers too. My 5.4 heads are Windsor heads. It will use the 4.6 intake also.