Get the biggest fan you can physically fit to either face of the radiator (if you don't have A/C I would recommend front mounting it - it looks a lot tidier from inside the engine bay and really opens up some space to swing a wrench or 2). It won't matter what brand you use but try to get one with a really good CFM rating - more flow = more efficient, and a fan that can push and pull air to save you confusion. You'll need the fan, a hose joiner/coupler kit so you can fit the sender switch into the bottom radiator hose, the sender switch and a relay kit. Depending on the fan you can get away with spending as little as $50 with some hunting on ebay.