The NHTSA website says that a car 25 years or older doesn't have to comply with FMVSS and would be eligible for importation:
"A motor vehicle that is at least 25 years old can be lawfully imported into the U.S. without regard to whether it complies with all applicable FMVSS. Such a vehicle would be entered under Box 1 on the HS-7 Declaration form to be given to Customs at the time of importation. If you wish to see that form, you may download a copy from our website at
www.nhtsa.dot.gov/cars/rules/import. You should note that the 25 year period runs from the date of the vehicle's manufacture. If the date of manufacture is not identified on a label permanently affixed to the vehicle by its original manufacturer, to establish the age of the vehicle, you should have documentation available such as an invoice showing the date the vehicle was first sold or a registration document showing that the vehicle was registered at least 25 years ago. Absent such information, a statement from a recognized vehicle historical society identifying the age of the vehicle could be used."
From what I've heard/read in the past is that were all SOL in the skyline r32 dept. though..