Of course, it all depends on the exact dimensions of the radiator you'll be using.
People say that 3-cores are better than 2-cores. Well, again, that all depends on the size/width of the exact radiator people are talking about.
FWIW: The FRPP 2-core aluminum radiator is wider and has far more cooling area than just about any 3-core radiator that people can find and will still squeeze into a stock Fox/sn95.