I dont think that you need the radiator support. I just picked up a JDM front end (consisting of both plastic H4 headlights, both clear single chamber sidemarkers, both wrap-around bumper lenses, bumper, and hood... I need to get the amber sidemarkers off Ebay or something), and I took out my stock headlight, and put the JDM headlight in, and it lined up with the factory USDM holes that hold the headlight in... because that was my main concern. If they wouldn't fit, then I'd need a radiator support.

Fenders are the same, like DJ said, so all you really need is the amber sidemarkers.

Only real problem that I need to do is to convert the headlight wiring to H4... thats all I have come across as far as any modifying.

If I come across or find anything else that needs modifying, or wont fit properly, I'll let you know.