I would not buy an aftermarket radiator. The tanks are made from foil. I'd put a 3 row core in there and you'll never have a problem. You might get away with just a rod out, but going from a 2row to a 3row is the best way. If you look at the bottom header, you should see a row of dimples if there's room for the 3row. My 3.5 had them in the SR. Bet yours is the same. If the core is not performing, all the fans in the world won't help. Do you have a fan shroud?

Not responsible for advice not taken...