Search eBay for 47-54 Chevrolet truck radiator. Scroll until you see one with the top tank which is shaped like what comes on an original brass radiator. That is what I use and they fit right and keep the engine temperature at 180, and you can prime and paint the top tank and the side and it will look original as all get out. A bit over $200.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission