i have a round tank rad that is technically for a cbody but has the same measurements for bolt to bolt as my 68. it measures about 24.5" form left to right bolt holes and about 13.75" top to bottom. the # is 2898074
I have an aftermarket one that was briefly in my 68 GTS with a small block. I think it's a Be-Cool aluminum radiator. If your interested, I can send you pics of it. Only used for a couple of months, guarantee no leaks. Excellent condition.