I came up with this idea awhile back, but never got around to doing it. I purchased a set of coupe fenders. the coupe fenders are longer than the sedan fenders, but the bolt holes are all in the same spot!
so, you need to marry the coupe and sedan fenders together via vutting and welding! that is the hardest part.
after that, it should be pretty much all bolt on.
the front radiator support is the same part number from nissan, so that shouldn't need to be changed.
you will need:
1) a pair of coupe fenders
2) coupe fender liners
3) pair of coupe headlights
4) coupe hood
5) coupe front bumper
6) coupe grille
that should be all.
you may want to check on www.g35driver.com
for more info. there is a thread on the conversion in the 2003-2006 Sedan section.