Sapporo Guy -
Motorex was a legal importer of Skylines into the US. They folded, and it depends who you talk to about why. Some say they federalized the R33, then tried importing R32's and R34's under the same ticket, other people say it had nothing to do with that, and that they were involved in other, shady businesses.
Anyway, it is way way way harder to import Skylines into the US then into Canada, Australia, NZ, or Britain. The US government has to be shown that they are US certifiable, and therefore crash tests have to be done, etc. I don't know, but doubt that you can use the Motorex file. Very few are importing Skylines into the US, and it is frequently said that those that do arrive, are there illegally.
In Canada we have a 15 year exemption, so any car can be imported once it has turned 15 years old. In the Toronto area, we have a lot of R32 GTR's (I debated between the 911 and the GTR, and I may yet pick up an R32). We also have some kei cars, believe it or not. I was talking to a guy a while back who has a Honda Beat, and is working on putting a Suzuki GSXR motor into it!
you can try these sites for more (and better) information -
http://gtrcanada.com/
http://www.gtr.co.uk/forum/upload/
http://tyndago.googlepages.com/home
As you have probably seen, there are a number of companies that specialize in exporting parts/used engines/front clips. A number of guys over there do this to supplement their income as english teachers. Actually, I am contemplating heading back to Japan, in which case, I'll be looking at doing similar.