I think that by 1960 it did not matter if the car had AC or not. Fan shrouds were fairly standard in most cars. If you cannot find a shroud or info on how to make one I think that I would put a thermostatic controlled electric fan on it. Several aftermarket companies sell them. A very large radiator might take 2 fans, but their are kits for them too. I don't think that they are terribly expensive either. Go to a performance parts website like Jegs or Summit and I think they will have them as they are commonly sold to racers and street rodders. Then you could ditch the stock fan and maybe gain a little efficiency benefit from not having the parasitic drag of the fan spinning when you don't need it. Good luck.