When I got the FAA CD on the airplane there was not a clear paper work trail. I don't know if the Canadian records ever find their way into the FAA data base or not. Plus, the seller plead ignorance of the airplane's history.
There's a flip-side to Canadian-registered planes. Our Canadian brethren can confirm or correct me, but I understand that when a plane is registered in Canada it is given a new set of logbooks. All of maintenance in Canada must be recorded in the Canadian logbooks, not continued in the originals. For the most part, the original logbooks cease being important - Transport Canada is only interested in the Canadian logs. With no requirement to keep the original U.S. logs, why bother remembering in which attic or 'circular file' they're stored? Registering an airplane in Canada is one way to launder the logbooks of a plane with a checkered history.