You could do a compression test on it that may tell you if the bottom end is gone but as escrst said it's hard to tell what it is without hearing it my self. As for the radiator if it's a series 1 engine thats been put in there then i think you can use a rad from a 1.3 if it's a series 2 engine then the turbo on it will be water cooled so you need a series 2 rad. If it's a series 2 rad it will have a small pipe coming out of the lefthand side as you look at the engine from the front of the car.