I would re-core it, if the tanks are still good. That way you know it will fit and work. You can also have stuff like drain cocks added when recoring- a very nice thing to have. Some aftermarket radiators aren't built very well and the fit is poor. I had a Jeep radiator re-cored and it turned out great, a lot better than the new aftermarket ones. It is a good idea to develop a relationship with a radiator shop so when you need your heater core done they can help you out. A lot of times the warranty on a re-cored unit is better than on a new one.
