If you keep up what they started... you can probably get 300,000 more out of it... a one owner with paperwork to boot... you really got lucky....If you decide not to get it.... post it here because someone is bound to jump on it...
Of course much depends on the price they are asking .... at some price it pays to have an independant with no future interest in the car test it.... like " lemon busters".... that type of company...cheap insurance in the long run... primarily compression readings.... the best overall indicator of the engine condition...