For almost 20 years we have supplied a high efficiency, 3 row radiator for the 1986-7 GN's that is a direct replacement. This core was developed years ago for dessert cooling and has proven to work as well as any radiator, including the alum ones.
With hundreds of them sold, there never has been any customer that has not been satisified with its performance. No adapters or mods are needed, and no worry about a plastic tank that can and will split, and it provides for both engine oil and trans coolers.
There are many choices for GN replacement radiators, and this is among the best.