Over 25 years is no problem, your customs broker will take care of it for you (my experience with 72 series III) you will need ownership docs and bill of lading. I picked mine up at the port, it was easy. The freight forwarder will let you know what duty you owe and give you a list of all of the charges and review your documents for you. They will also tell you what originals you will need and what can be copies.
72 Series III 109 SW Diesel, 03 RR, 98 Porsche 986, 01 Porsche 986 3.6 L