Honda says studying shift overseas to avoid yen effect

* Working under assumption of 80 yen to dollar over next 3 years* Exports from Japan unsustainable at current dollar-yen rate -CFO* Discussion of shifting output to continue until last minute -CFO* Not optimistic that yen will weaken -CFO* Honda move could put pressure on Toyota, Nissan (Adds details)By Chang-Ran Kim, Asia autos correspondentTOKYO, Aug 9 (Reuters) - Honda Motor Co is studying