67 V8 radiator in a 66

Sure looks it. Time for tape measure, paper and pencil.
When I've had to get replacement radiators, I've used cardboard to trace over the mounting flanges etc of the radiators and the openings. It helps when figuring when figuring out what's different.

Like this - which is a 68 with 70 bottom tank.
IIRC the 70 tank is taller than the 68-9 tank so the core has to be shorter.
View attachment 1715489953

First try didn't fit.
View attachment 1715489954

View attachment 1715489955
thank you for your insight on this , I will go out today and bolt it in and see how high it wants to set, this is a custom build radiator because the lower hose is on the passenger side like the later models, I hope it will work for me , if not I need to get started saving for an aluminum radiator.
Thank you Mattax