When I got the car EVERTHING under the hood was black, possibly correct, but kind of boring! I think the color will liven things up. Pictures just don't bring out the "look" of the wrinkle finish, it is not at all like an "under coating" appearance.
What year did Ford switch from Black to Blue for engines? 65-66?
Note the deeper "skirt" on the original "pop-up" high compression piston. The new one has a "dished" top end to reduce the compression ratio.
I use "plasti gauge" to double check clearances after measuring. You can't be "to sure" and lot's of professional engine builders also use it in the final assembly steps.