I have a radiator that I would make you a deal on...
Its for a 65 but will work in a 60-66. It is an original Harrison, rebuilt with 3 core innerds, (apparently as heavy duty as you can get-according to my radiator man). Its pretty much the equivalent to a 4 core like for a 454 truck, so it cools excellent. It has never been used since it has been rebuilt.