There is some minor difference between '67 and '68-9 radiators and shrouds.
Maybe the shroud mounting holes? But really have no idea. . Maybe ask in cooling what the difference is.
Here's the '68-9 shroud (repro)
The fan opening is about 20"
Center of the fan opening is about 10" from the passenger side shroud mounting holes
Vertically the rightside mounting holes are about 2 1/4" and 15 3/8" about the bottom line.