It has been a while, but I don't believe the 68 and 69 are a true exchange, I think the flanges bolt up differently by the core support.
You can put a 68 on the 69 core support easily , the 69 on a 68 core support requires mods , it will not bolt on without at least removing a bracket that goes across the top of the radiator cross bar.
For 68 the hood bumper is on the core support, in 69 it is on a bracket that is attached to the fender in the same spot.