You'll need more than the heads. You'll need the front cam chain cover, cam drive chains, etc. There are also oiling changes in the 05 to handle the VCT. W/O the 05 computer you won't be able to run the VCT, but I imagine for your application you'll be removing the VCT anyway.
Unless you have lots of cash & time to burn figuring out how to stick 3V heads on the old iron block, my recomendation is that you port your stock 2V heads or go with aftermarket 2V heads. There are lots of parts including S/Cs designed for the 4.6 2V.