im useing an ebay special aluminum radiator for a s13 in my supra, its basicly a koyo knock off. this is with no fan, and it never overheats in florida heat and in traffic. i can make it overheat if i leave the car ideling for aound 30mins wile stoped. and if i go slide the car around for about 10mins it will overheat, (near redline and little airflow) but other then those odd cases it runs great.
i would say any aluminum radiator would work fine as long as its not an minicoper radiator ;-)