As long as the aircraft you want has all the build logs, and is currently Airworthy in Canada it's pretty easy.
In my case my a/c was originally built and certified in the US, the. Sold to Canada, the guy flew it for a few years and kept all the logs and docs.
So all I have to do was fly it down, de Register it from Canada and receive that doc, then fill out the new reg form from the FAA and attach the de reg from Canada.
Once they issue the registration then you have to do the conditional inspection and get a fed to come take a look.
Prove to him all the papers are in order and you think it's Airworthy, it takes time is all.