... If they don't accept the overhaul,, well time to say goodbye to the plane,, regardless of look or condition. That is, unless you still want it,, but more then likely to get it imported you'd have to have the engine O/H here or in the US by an approved facility.
Are the engine overhaul rules that much different in Canada? Here in the US, any A&P can overhaul an engine. The engine manufacturer specifies what must be done to call it an overhaul, not the FAA. Just like anything else, some overhaulers do the bare minumum (service limits on everything with a wear limit, rebuilt/reconditioned cylinders, accessories, etc) while others do a more comprehensive (i.e. expensive) overhaul to new limits with new cylinders and accessories--the sky's the limit. I've seen some shadetree mechanics do fantastic work and I've seen some "approved facilities" do less than fantastic work. It really pays to do research and get it down in writing what was done in an overhaul to determine what was done beyond the minimums specified by the manufacturer.