I have a 67 coupe and was looking at Summit Raditor for it. They list it for a 65-66 and 69-70 but no 67 68. Will the Rads for the 65-66 fit? The size is close but not exact.
the 65-66 is going to be a bit too narrow... the mounting holes will be suspended in midair... i think the 69-70 will be a closer fit. (im sure someone will correct me if im wrong)
I agree that the 65/66 radiator would not be a good option due to its smaller cooling capacity. In your case I would opt for a 69' radiator, which should be easy to adapt to your 67/68 radiator support opening.
One word of caution though about the 69/70 radiator. Make sure that the lower radiator hose is located on the same side as your water pump inlet. A 69' SB radiator would have the lower hose on the passenger's side, whereas a 70' would be on the driver's side.