Wasn't trying to loose you on the milling question. I believed you were describing more the idea of getting the appearance right on the housing. I am speaking more to functionality. I am trying to learn of the difference of the gasket face of the housings. I don't know for sure, only assuming the gasket face of either of the 67 housings is a flat plain with just a recess around the hole for the thermostat to fit in? The picture I included is for the housing I have and what appears to me a C8AE-8594-B and was trying to get to seal up on my C7AE 9425-E intake. I referred to milling the gasket face to get it flat for functionality not overall appearance. But now I guess I am learning that there is a magic date of Dec 66 so that changes things.
My Cougar had a scheduled build date of Oct 28, but was actually built 11-1-66.
The problem with my car is it is a "basket" of parts pulled together as it was incomplete when I bought it. Perhaps I should refrain from asking questions here as I am not going for concours but trying to make a nice looking car that functions right.
Thanks for you input