Front cover, and depending on if you wanted to keep variable cam timing a 05+ computer would be needed. Or just get some cam lock out tools and run it that way. You would also have to do something about the throttle cable since the 05s are drive by wire.
i'd recomend skipping the 3v and going 4v. alot easier swap and far more performance and aftermarket available for the 4v. unless ur just wanting to go 3v for a particular reason. the cpu and drive by wire will be ur biggest problems to overcome. just my .02